The number of images has never been growing as fast as it is now. If you get your images from an experienced photographer or a reputable photo company, you can use them with confidence most of the time. But there are also many times when the pictures you get have poor contrast and severe color casts. For example, they come from poor picture discs, or digital cameras and scanners with poor quality, or many free pictures on the Internet. Then when using Previously, it was necessary to modify an image, and sometimes a “good” image needed further processing.
There is a controversial comment: No matter who is engaged in image editing, he must be familiar with curves, and their application is as natural as breathing. This statement is bold enough! Has it caught your attention? If I were forced to give up all image adjustment tools except one, then I would definitely choose curves! Experts believe that curves are what you use The first of many ways to improve image quality!
Now, let’s clear up some misunderstandings immediately:
Curve is not a filter, it is to make some adjustments to the image on the basis of being faithful to the original image, unlike filters that can create out-of-nowhere effects;
Curves are not that elusive. As long as you master some basic knowledge, you can master filters as quickly as you master other tools;
Controlling the curve can bring you more dramatic works, and more excitement will come from your hands;
Curves will not directly add points to your image, nor can they help you attract the attention of the opposite sex – except your boss!
One of the real pleasures that Photoshop gives you is that the software provides you with many solutions to difficult problems. As far as adjusting images is concerned, in the Image>Adjustment menu, you have many tools to choose from. The reason I like Curves the most is that with just this one tool you can:
Adjust the contrast of the entire or individual channels;
Adjust the brightness of any part;
Adjust the color.
Curves can accurately adjust images, giving new life to images that should have been scrapped!
Although this article is biased towards Photoshop, (especially the illustrations), the curve adjustment function is important to everyone who works with images, so even if you don’t use Photoshop, you can You can get a lot of useful help from it. There are no special effects using curves in this article, although that certainly falls under the category of special effects. This article is helpful for non-experts who edit images every day to make them look better. Believe me, after reading this article, the curve will become your right-hand assistant, just like the hammer is to the carpenter!
Now, let us unveil the mystery of curves bit by bit!
Open the Image > Adjustments > Curves command, shortcut Ctrl+M, and the Curves dialog box will appear. (Figure 01) If necessary, we will explain each detail separately. Now let’s prepare some basic knowledge. If your screen looks different from the picture, hold down Alt and click within the grid to switch between large and small grids. The grid size has no effect on the curve function, but a smaller grid can help you adjust the curve. Good observation. Also note the two small triangles in the middle of the grayscale strip. The default for RGB images is black on the left and white on the right, that is, from the dark area to the bright area of the image, while the default for CMYK images is exactly the opposite. (Fig. 02) To avoid confusion, I recommend that you set it to a mode you are familiar with before adjusting. The standard curve will give you more intuitive understanding. ◎
Picture 02
First of all, one of the most obvious facts is that there is no curve change now! Why? You must know that the curve reflects the brightness value of the image. A pixel has a certain brightness value that you can change to make it brighter or darker. Look at these two pictures (Figure 03, 04). The horizontal grayscale bars below represent the tone of the original image, and the vertical grayscale bars represent the adjusted image tone. Without any changes, the input and output tonal values are equal, so the curve is a straight line at 45 degrees, which is why there is no change in the curve. When you make a change to any point on the curve, you also change the corresponding pixels of the same brightness on the image. Click to establish an adjustment point. This point can be dragged to any range within the grid. Whether it is bright or dark depends on whether you are up or down. A sudden change in the brightness value will create a very eye-catching effect; a slow and gradual change, whether it is increasing or decreasing the brightness value, will make the tone transition smooth and the effect realistic. The following example demonstrates what happens to the image when certain values on the curve are changed, and you can clearly see the shape of the curve changing. (To show the effect, in thisThe curves in the image are all a bit exaggerated, and sometimes you need strongly varying curves, but most of the time, the image curve changes much more gently. )◎
Chapter 2: Application of Curves in Grayscale Images
After a period of explanation, we finally reached the actual operation stage. In this part, we will first process a grayscale image to lay the foundation. Color images will be discussed in the next chapter. Now let’s take a look at this poor image (Fig.05): captured with a digital camera on a dark evening, it lacks contrast and the pixels are too concentrated in the mid-tone range. You may also encounter something like this at work. Can we use curves to improve? The answer is yes.
Figure 061-062: Original picture and curve, the adjustment point has not changed; ◎
Figure 071-072: Increase the brightness of the adjustment point and the overall picture will become brighter; ◎
Figure 081-082: Reduce the brightness of the adjustment point and the overall picture will become darker. ◎
You may have discovered that neither raising nor lowering the curve brightness alone completely solves the problem. They improve one part of the image while destroying another. If we can learn from each other’s strengths, the problem will be solved. Another feature of curves is that multiple adjustment points can be added. Add adjustment points anywhere in the image and adjust them individually, so that you can adjust areas with different brightness and color values. For this image, two adjustment points work well: increasing the brightness value in the bright areas and decreasing the brightness value in the dark areas. (Picture 091-092)◎
You may have discovered that neither raising nor lowering the curve brightness alone completely solves the problem. They improve one part of the image while destroying another. If we can learn from each other’s strengths, the problem will be solved. Another feature of curves is that multiple adjustment points can be added. Add adjustment points anywhere in the image and adjust them individually, so that you can adjust areas with different brightness and color values. For this image, two adjustment points work well: increasing the brightness value in the bright areas and decreasing the brightness value in the dark areas. (Picture 091-092)◎After seeing this information,
Tips: Hold down Shift to select multiple adjustment points. If you want to delete a certain point, you can drag the point outside the curve coordinate area, or hold down Ctrl and click the point. In fact, in an image like this, where there are no highlights or shadows, I would initially narrow down the curves to increase the contrast. As we have said before, any point within the grid can be moved, including of course the two end points of the curve. If we make sure the “curve” is straight and move the dark endpoint of the curve to the right and the light endpoint to the left, the curve becomes steeper, increasing the contrast of the midtones. (Figure 10) This method is very useful for most mid-tone images that lack contrast! Similar to it, adjust the sliders at both ends of the color scale to focus them toward the middle. Granted, in this example, it might be more clear using the Levels tool. (Using the Curves tool does not mean that you cannot use color levels, changes, etc. Here, “any means” to achieve the goal is not a bad thing) Here is a little trick that allows you to quickly create an inversion effect: Move the black endpoint from the bottom on the left to the top, and move the white endpoint from the top on the right to the bottom, so you can achieve the same effect without using the invert command. Now you may be thinking: not every picture has highlights and shadows like this.�. That’s right! But most of them are like this. If you use it wisely, all your images will look stylish! ◎
We have the theoretical foundation, and here are three top-secret weapons, enough to earn the respect and admiration of your well-informed colleagues. These three tricks are equally useful on grayscale images and color images, but for convenience, we still use grayscale images as an example. Don’t miss it!◎
Tip 1: Use the eyedropper tool to set the range◎
Did you notice the part in Figure 11? The preview window allows you to see the changes made, so be sure to open it. Use the “Auto” option with caution, as clicking this button will cause the brightest pixels in the image to turn white and the darkest pixels turn black. (Figure 12) Of course, this will bring convenience to those who need to save time, but abandoning manual adjustments and adopting automatic methods will rarely provide the best results. This approach is even more dangerous when the middle values of the color image are assumed to be the lightest and darkest values! In many cases you will want to specify the lightest and darkest parts of the image yourself, It is particularly prominent when dealing with special effects pictures. You can do this with the eyedropper tool. Select the black eyedropper on the left and click in the image window where you want it to be black, and the same for white. Since our example image is a grayscale image, the grayscale straw is useless here. Fast and precise! If you are preparing an image for printing and need more certain color values, double-click the eyedropper to bring up the color dialog box, where you can set precise values. ◎Xuan
Tip 2: Check the brightness value on the curve◎
This is a cool trick: if you want to know the definite value of any point on the image, you can move the mouse to the image window, the pointer turns into a straw, and click on the place you want to view. A point corresponding to this point will appear on the curve. This method is very useful when you need to change the brightness value of a specific place without knowing its position on the curve. Worried about not remembering the exact location? Don’t worry, Photoshop has already thought of this for you. While clicking on the image, hold down the Ctrl key so that the point will be fixed. (Picture 13)◎
Tip 3: Strengthen the contrast in specific places This method is based on the previous method. We will optimize the image, that is, highlight the theme of the picture. Many pictures have a fixed theme, such as people in the environment, etc. Most of the time, we do more with this theme than the background picture. As the saying goes: If there is steel, it must be used on the blade. In the case of limited energy, we should try our best to focus on the most important parts and highlight the center. We have just seen that a steep curve will increase the contrast of the image. Now hold down Ctrl and click around the screen to find the corresponding point on the curve. You can take multiple points, keep the top and bottom ones, and delete the others. Now you know where to work on those parts of the curve. Increasing the slope of the curve will result in more detail. That is, don’t be too bright or too dark, try more and try to balance it with the picture. Sometimes the range taken is a little wider, and that’s not a bad thing, it’s just background. (Figure 14
The following example is what I just said. The curve is as shown in the figure. (Figure 151-153)◎
With the accumulation of experience, you can slowly see the position of the pixels of each tone on the curve. The more you see, the more you can determine which ones should be highlighted and which ones should be highlighted. Go dark and you’ll know better. This rough analysis is necessary before adjusting the curve. Once placed, these adjustment points can still be moved. You will find that when you place and start adjusting these points, the preview window is as intuitive as your canvas. When the position of the adjustment points and the inclination of the curve change under your hands, the image also changes according to your wishes. You don’t have to limit yourselfAt one or two points. (Although Photoshop allows you to place up to 16 adjustment points, in general, two points are enough.) The adjustment process will become fast and effective! Of course, the premise of all this is that you must practice more. ◎.
There is another thing you need to understand: curves cannot be separated from the picture, and there are no curves that can be used everywhere like snake oil. Each picture is unique, so its curves are also unique. The optimal curve shape may vary significantly between images. The center of the image is also different, some are bright (polar bear on the glacier), some are dark (black cat on the coal pile in the basement), and some are mid-tone (like the people in the example above). Now you know how to work with different images: use the mouse to click on the range to be adjusted; mark on the curve; change the slope of the curve to increase contrast. Below are two examples. (Figure 16, 17)◎
Chapter 3: Use Curves to Improve Color Images The color images we refer to here refer to RGB images, excluding CMYK mode images. You may be thinking about the time I spend on grayscale images and If you’re working with a disproportionate number of grayscale images, or you’re wondering how to apply curves to color images, well, let’s move on to Chapter 2. For color images, the theory is very simple, and if you figured it out in Chapter 2, you’re in good hands now. An RGB image can be thought of (and it is) as consisting of a composite channel and three grayscale channels that each contain a brightness value for a color. If you haven’t noticed this, then open the channel panel, click on different channels, and you will see grayscale images with different brightness. This way, you can edit each channel individually with curves just like you would a grayscale image. Subtly adjusting each channel is the most accurate and reliable way to adjust color in Photoshop. You can skip color balance entirely and save yourself the Hue/Saturation or Change commands, because we have better ones! When you call the Curves command on an image in RGB mode, the composite channel information will appear in In the information bar in the default position of the screen: RGB. If the color is satisfactory and the only difference is lightness and contrast, adjust the curves in the composite channel in the same way as the grayscale channel. If the color itself needs to be modified, things get a little more complicated. So how to start? Where to start? To start, you need to evaluate the color distribution and the proportion of each color in the image to eliminate the discordant parts. A big mistake people often make when starting out is that they rush into a color selection tool that doesn’t feel right for them. In fact, if you can see a color like this in one part of an image, there’s a good chance it will permeate the entire image and be published. If such a color appears, how do you determine this color? ◎Xuan
Let me introduce you to a very useful tool: the information panel. If not, open it from a window and give it a permanent place on your desktop. (Figure 18) No matter what tool you are currently selecting (with the exception of the text tool), place the mouse pointer on the screen, and the color information of the pixel under the pointer will appear in the information panel. Only knowing how to use numbers to adjust color can truly be considered a mastery of color correction. We won’t go into too much detail about numerical values in this article, but this method is very different from other methods. Just remember one fact when you adjust colors: a neutral-colored pixel, its RGB value should be equal. No matter what they are, they are all equal. Color values vary greatly from light gray to dark gray, but if its R=G=B, then it is neutral. Our eyes and brains are highly adaptable and work together to give objects what the brain perceives as black, white or neutral color. Color is easy to estimate from the monitor, but black, white, and especially neutral colors should be determined from the information panel. Sorry! I can’t tell you what color your skin should be, or what values are appropriate for green grass or navy, but neutral colors can serve as your reference point. Of course, not every image has neutral colors in it, but if you take a look, you’d be surprised how many images use neutral reference points: a white shirt, the tires on a truck, a picture on a table Paper, asphalt on a stone pavement, white fence, granite construction…you get the idea, if you need a neutral color the chances of finding it in one object are 100%. So how do you select those pixels with the color shown in the information panel? It’s certainly not a neutral color, the blue value is much smaller than the red and green values. What’s the opposite color of blue? It’s a beautiful yellow. assume it to be neutralColor, we add blue to other colors. ◎
When you first see the picture below (Picture 19), you may have a clear impression: there must be something wrong with this picture! This is a picture taken with a digital camera When looking at studio images, we often think of it as the lack of red in the studio lighting, which results in a greenish image. But the combination of light and camera in this case is more yellowish than greenish. How do we know? Well, let’s illustrate by looking at a potentially neutral reference point for an image. Place your mouse pointer over any pixel in the image that you think might be a neutral color, and the information panel once again tells you that blue is severely lacking. Now you understand!◎
It is the reference point I selected (Figure 20) and the information panel display (Figure 21), as well as the corrected image (Figure 22). ◎
I have spent a lot of space describing how to use neutral colors to eliminate color casts, but not all images need to be like this! When the tone of an image needs to be warmer or more You only need to do this when it is cold so that it can better match with other images. For example, you need to add russet to exaggerate the sunset or bright light shining on the lawn. Add a touch of red to the skin of your face or remove some yellow from a dusk photo. It’s no problem for you. Similar to increasing or decreasing contrast, you can do it with curves. Find the source of the problem in the information panel and select the problematic channel in the curve dialog box to quickly eliminate the problem. When you move the mouse from the image window to the curve dialog box, the prompt message in the information panel will disappear. If you change one or more points on the curve, when the mouse returns to the image window, the difference between before and after the change will be displayed in the information bar (Figure 23). Also, as we have said before, you can determine points on the curve by holding down Ctrl and clicking within the image. In color images, this function is more useful: if you are in a monochrome channel, click to place a point. That’s OK; but what if multiple channels need to be placed with multiple points? Repeatedly clicking on the points to be selected in the image window is not a pleasant thing, and it is difficult to ensure that the same point is selected every time. At this time, the color sampler tool hidden under the eyedropper tool can be of great help to you. Click on the image to place a reference point, and the color information of the labeled reference point will appear in the information panel. Now just adjust the curve by referring to the numerical value. ◎
Keep sampling, remember the three eyedropper tools we mentioned earlier? They allow you to set a specific color for the image under the mark. For images with special requirements, this is very useful. For example, if you need the brightness of the image to be in the range of 250, 250, 250 and 5, 5, 5, just set the white and black straws respectively. Combined with the neutral colors we described earlier, you probably already know the grayscale The straw works. Most of the time, I’d rather use a curve, but an eyedropper is also a pretty hand-friendly tool. Sometimes I also use Auto Curve, which makes the darkest pixels black and the brightest pixels white within each channel, which is fine some of the time, but usually it creates strong colors and contrast . The preview window will reflect the changes to you. If you are not satisfied, hold down Alt and “Cancel” will become “Reset”. What is there to worry about now? ◎ We have seen so much about the entire image, but You also sometimes have to look at when curves are applied to local selections. Sometimes the foreground and background colors don’t match, sometimes the background is too dark and the object is just right…many situations must be taken into account. After making all possible adjustments to the image, we can also use the selection tool to select a selection and use curves to make local adjustments. Curves work within selections as well as within channels.
Additional explanation:
The following 4 tips will make your work easier.
1. Fading curve Shortcut key: Shift+Ctrl+F. Sometimes you do a good job, but it seems a bit “over”, and you don’t want to use the Undo command to bury your achievements. In this case, you can use the “Fade” command to lighten the curve effect. As the quantity decreases, the effect becomes less and less obvious. However, remember: it must be done after you have just used the curve.��Fade can only be used before using other commands, otherwise your next command will fade
2. Undo and redo If you are not satisfied with the curve effect you just made, you can use Ctrl+Z to eliminate it like other Photoshop commands; you already know the shortcut of the curve command The key is Ctrl+M, but did you know that if you hold down Alt+Ctrl+M, the dialog box will open with the last curve set? This way you can continue to adjust. This is not like method 1, which is a lightening effect based on the original adjustment, but a completely new adjustment. Of course, if you want, you can also make adjustments based on the original. It is not like the fade command, which can only follow the previous command. During the working time of Photoshop, it can remember the position of the last curve. What is its use? If you need to do the same curve processing on 6 more pictures, then you only need to make a curve adjustment once, then press the shortcut key, and the remaining 5 pictures can make the same adjustments as the first one. In addition, the level, saturation, and color balance commands can also work in the same way
3. Batch processing If you want to record some representative curve types so that you can apply them to similar pictures next time, then method 2 is helpless. At this time we can use storage command to store an adjusted curve shape in a fixed folder, and then use Photoshop’s Action command to record and load the curve. In this way, you can quickly process a large number of pictures with the same curve. ◎
4. Adjustment layer
This is my last resort. Each new version of Photoshop brings new features that make it easier and easier to use, like the new adjustment layers, which allow you to make unlimited changes to an image without destroying it. Open Layer > New Adjustment Layer, select Curve (Figure 24) (or something else) in the drop-down menu, the layer properties dialog box appears, see the automatically named Curve N, click OK and the previous one will appear. The same curve dialog box, where you can adjust the image. If you are not satisfied, double-click the layer thumbnail and you can continue to adjust based on the previous one, just like method 2 we just mentioned, the difference is , you can adjust the curves at any time before flattening the layers. It won’t damage the actual pixels, so you can use it with confidence. Behind the layer mask, you can protect certain parts from the curves. Don’t forget this tip! The more you change an image, the more you need to keep it as pristine as possible, especially if it’s something bizarre. Let me tell you some personal experience: you only need to perform this little trick once on many layers, and countless magazine covers will go crazy for it! ◎
Special effects
You have mastered the powerful curve function and know what it can do for you, but after saying so much, some people still feel that it is not enough without using curves to create some special effects. Okay, Here I will give you the simplest and most commonly used special effect, which is usually used to express highly reflective materials such as metal and glass. It’s very simple, so I won’t talk nonsense. Basically, it’s blur, then adjust it with curves, and finally use the hue/saturation command to color it, as shown in Figure (25-29). ◎
We know so much about curves that we can basically handle them. To gain more experience, we need to explore by ourselves in practice. Well, I hope this article can be helpful to you! ◎
The number of images has never been growing as fast as it is now. If you get your images from an experienced photographer or a reputable photo company, you can use them with confidence most of the time. But there are also many times when the pictures you get have poor contrast and severe color casts. For example, they come from poor picture discs, or digital cameras and scanners with poor quality, or many free pictures on the Internet. Then when using Previously, it was necessary to modify an image, and sometimes a “good” image needed further processing.
There is a controversial comment: No matter who is engaged in image editing, he must be familiar with curves, and their application is as natural as breathing. This argument is bold enough! Has it caused a stir?���Notice? If I were forced to give up all but one of my image adjustment tools, it would be Curves! Experts agree that Curves are the number one method you can use to improve image quality. !
Now, let’s clear up some misunderstandings immediately:
Curve is not a filter, it is to make some adjustments to the image on the basis of being faithful to the original image, unlike filters that can create out-of-nowhere effects;
Curves are not that elusive. As long as you master some basic knowledge, you can master filters as quickly as you master other tools;
Controlling the curve can bring you more dramatic works, and more excitement will come from your hands;
Curves will not directly add points to your image, nor can they help you attract the attention of the opposite sex – except your boss!
One of the real pleasures that Photoshop gives you is that the software provides you with many solutions to difficult problems. As far as adjusting images is concerned, in the Image>Adjustment menu, you have many tools to choose from. The reason I like Curves the most is that with just this one tool you can:
Adjust the contrast of the entire or individual channels;
Adjust the brightness of any part;
Adjust the color.
Curves can accurately adjust images, giving new life to images that should have been scrapped!
Although this article is biased towards Photoshop, (especially the illustrations), the curve adjustment function is important to everyone who works with images, so even if you don’t use Photoshop, you can You can get a lot of useful help from it. There are no special effects using curves in this article, although that certainly falls under the category of special effects. This article is helpful for non-experts who edit images every day to make them look better. Believe me, after reading this article, the curve will become your right-hand assistant, just like the hammer is to the carpenter!
Now, let us unveil the mystery of curves bit by bit!
Open the Image > Adjustments > Curves command, shortcut Ctrl+M, and the Curves dialog box will appear. (Figure 01) If necessary, we will explain each detail separately. Now let’s prepare some basic knowledge. If your screen looks different from the picture, hold down Alt and click within the grid to switch between large and small grids. The grid size has no effect on the curve function, but a smaller grid can help you adjust the curve. Good observation. Also note the two small triangles in the middle of the grayscale strip. The default for RGB images is black on the left and white on the right, that is, from the dark area to the bright area of the image, while the default for CMYK images is exactly the opposite. (Fig. 02) To avoid confusion, I recommend that you set it to a mode you are familiar with before adjusting. The standard curve will give you more intuitive understanding. ◎
Picture 02
First of all, one of the most obvious facts is that there is no curve change now! Why? You must know that the curve reflects the brightness value of the image. A pixel has a certain brightness value that you can change to make it brighter or darker. Look at these two pictures (Figure 03, 04). The horizontal grayscale bars below represent the tone of the original image, and the vertical grayscale bars represent the adjusted image tone. Without any changes, the input and output tonal values are equal, so the curve is a straight line at 45 degrees, which is why there is no change in the curve. When you make a change to any point on the curve, you also change the corresponding pixels of the same brightness on the image. Click to establish an adjustment point. This point can be dragged to any range within the grid. Whether it is bright or dark depends on whether you are up or down. A sudden change in the brightness value will create a very eye-catching effect; a slow and gradual change, whether it is increasing or decreasing the brightness value, will make the tone transition smooth and the effect realistic. The following example demonstrates what happens to the image when certain values on the curve are changed, and you can clearly see the shape of the curve changing. (In order to show the effect, the curves in this example are somewhat exaggerated. Sometimes you need strongly changing curves, but most of the time, the changes in the image curve are much slighter.) ◎
Chapter 2: Application of Curves in Grayscale Images
After a period of explanation, we finally reached the actual operation stage. In this part, we will first process a grayscale image to lay the foundation. Color images will be discussed in the next chapter. Now let’s take a look at this poor picture (Fig. 05): This is a photo taken with a digital camera in a dark place.The picture was captured late, and it lacked contrast, with pixels too concentrated in the mid-tone range. You may also encounter something like this at work. Can we use curves to improve? The answer is yes.
Figure 061-062: Original picture and curve, the adjustment point has not changed; ◎
Figure 071-072: Increase the brightness of the adjustment point and the overall picture will become brighter; ◎
Figure 081-082: Reduce the brightness of the adjustment point and the overall picture will become darker. ◎
You may have discovered that neither raising nor lowering the curve brightness alone completely solves the problem. They improve one part of the image while destroying another. If we can learn from each other’s strengths, the problem will be solved. Another feature of curves is that multiple adjustment points can be added. Add adjustment points anywhere in the image and adjust them individually, so that you can adjust areas with different brightness and color values. For this image, two adjustment points work well: increasing the brightness value in the bright areas and decreasing the brightness value in the dark areas. (Picture 091-092)◎
You may have discovered that neither raising nor lowering the curve brightness alone completely solves the problem. They improve one part of the image while destroying another. If we can learn from each other’s strengths, the problem will be solved. Another feature of curves is that multiple adjustment points can be added. Add adjustment points anywhere in the image and adjust them individually, so that you can adjust areas with different brightness and color values. For this image, two adjustment points work well: increasing the brightness value in the bright areas and decreasing the brightness value in the dark areas. (Picture 091-092)◎After seeing this information,
Tips: Hold down Shift to select multiple adjustment points. If you want to delete a certain point, you can drag the point outside the curve coordinate area, or hold down Ctrl and click the point. In fact, in an image like this, where there are no highlights or shadows, I would initially narrow down the curves to increase the contrast. As we have said before, any point within the grid can be moved, including of course the two end points of the curve. If we make sure the “curve” is straight and move the dark endpoint of the curve to the right and the light endpoint to the left, the curve becomes steeper, increasing the contrast of the midtones. (Figure 10) This method is very useful for most mid-tone images that lack contrast! Similar to it, adjust the sliders at both ends of the color scale to focus them toward the middle. Granted, in this example, it might be more clear using the Levels tool. (Using the Curves tool does not mean that you cannot use color levels, changes, etc. Here, “any means” to achieve the goal is not a bad thing) Here is a little trick that allows you to quickly create an inversion effect: Move the black endpoint from the bottom on the left to the top, and move the white endpoint from the top on the right to the bottom, so you can achieve the same effect without using the invert command. Now you may be thinking: not every picture has lights and darks like this. That’s right! But most of them are like this. If you use it wisely, all your images will look stylish! ◎
We have the theoretical foundation, and here are three top-secret weapons, enough to earn the respect and admiration of your well-informed colleagues. These three tricks are equally useful on grayscale images and color images, but for convenience, we still use grayscale images as an example. Don’t miss it!◎
Tip 1: Use the eyedropper tool to set the range◎
Did you notice the part in Figure 11? The preview window allows you to see the changes made. It must be�Open. Use the “Auto” option with caution, as clicking this button will cause the brightest pixels in the image to turn white and the darkest pixels turn black. (Figure 12) Of course, this will bring convenience to those who need to save time, but abandoning manual adjustments and adopting automatic methods will rarely provide the best results. This approach is even more dangerous when the middle values of the color image are assumed to be the lightest and darkest values! In many cases you will want to specify the lightest and darkest parts of the image yourself, It is particularly prominent when dealing with special effects pictures. You can do this with the eyedropper tool. Select the black eyedropper on the left and click in the image window where you want it to be black, and the same for white. Since our example image is a grayscale image, the grayscale straw is useless here. Fast and precise! If you are preparing an image for printing and need more certain color values, double-click the eyedropper to bring up the color dialog box, where you can set precise values. ◎Xuan
Tip 2: Check the brightness value on the curve◎
This is a cool trick: if you want to know the definite value of any point on the image, you can move the mouse to the image window, the pointer turns into a straw, and click on the place you want to view. A point corresponding to this point will appear on the curve. This method is very useful when you need to change the brightness value of a specific place without knowing its position on the curve. Worried about not remembering the exact location? Don’t worry, Photoshop has already thought of this for you. While clicking on the image, hold down the Ctrl key so that the point will be fixed. (Picture 13)◎
Tip 3: Strengthen the contrast in specific places This method is based on the previous method. We will optimize the image, that is, highlight the theme of the picture. Many pictures have a fixed theme, such as people in the environment, etc. Most of the time, we do more with this theme than the background picture. As the saying goes: If there is steel, it must be used on the blade. In the case of limited energy, we should try our best to focus on the most important parts and highlight the center. We have just seen that a steep curve will increase the contrast of the image. Now hold down Ctrl and click around the screen to find the corresponding point on the curve. You can take multiple points, keep the top and bottom ones, and delete the others. Now you know where to work on those parts of the curve. Increasing the slope of the curve will result in more detail. That is, don’t be too bright or too dark, try more and try to balance it with the picture. Sometimes the range taken is a little wider, and that’s not a bad thing, it’s just background. (Figure 14
The following example is what I just said. The curve is as shown in the figure. (Figure 151-153)◎
With the accumulation of experience, you can slowly see the position of the pixels of each tone on the curve. The more you see, the more you can determine which ones should be highlighted and which ones should be highlighted. Go dark and you’ll know better. This rough analysis is necessary before adjusting the curve. Once placed, these adjustment points can still be moved. You will find that when you place and start adjusting these points, the preview window is as intuitive as your canvas. When the position of the adjustment points and the inclination of the curve change under your hands, the image also changes according to your wishes. You don’t have to limit yourself to one or two points. (Although Photoshop allows you to place up to 16 adjustment points, in general, two points are enough.) The adjustment process will become fast and effective! Of course, the premise of all this is that you must practice more. ◎.
There is another thing you need to understand: curves cannot be separated from the picture, and there are no curves that can be used everywhere like snake oil. Each picture is unique, so its curves are also unique. The optimal curve shape may vary significantly between images. The center of the image is also different, some are bright (polar bear on the glacier), some are dark (black cat on the coal pile in the basement), and some are mid-tone (like the people in the example above). Now you should know how to deal with different pictures: use the mouse to click on the range that needs to be adjusted.circumference; mark on the curve; change the slope of the curve to increase contrast. Below are two examples. (Figure 16, 17)◎
Chapter 3: Use Curves to Improve Color Images The color images we refer to here refer to RGB images, excluding CMYK mode images. You may be thinking about the time I spend on grayscale images and If you’re working with a disproportionate number of grayscale images, or you’re wondering how to apply curves to color images, well, let’s move on to Chapter 2. For color images, the theory is very simple, and if you figured it out in Chapter 2, you’re in good hands now. An RGB image can be thought of (and it is) as consisting of a composite channel and three grayscale channels that each contain a brightness value for a color. If you haven’t noticed this, then open the channel panel, click on different channels, and you will see grayscale images with different brightness. This way, you can edit each channel individually with curves just like you would a grayscale image. Subtly adjusting each channel is the most accurate and reliable way to adjust color in Photoshop. You can skip color balance entirely and save yourself the Hue/Saturation or Change commands, because we have better ones! When you call the Curves command on an image in RGB mode, the composite channel information will appear in In the information bar in the default position of the screen: RGB. If the color is satisfactory and the only difference is lightness and contrast, adjust the curves in the composite channel in the same way as the grayscale channel. If the color itself needs to be modified, things get a little more complicated. So how to start? Where to start? To start, you need to evaluate the color distribution and the proportion of each color in the image to eliminate the discordant parts. A big mistake people often make when starting out is that they rush into a color selection tool that doesn’t feel right for them. In fact, if you can see a color like this in one part of an image, there’s a good chance it will permeate the entire image and be published. If such a color appears, how do you determine this color? ◎Xuan
Let me introduce you to a very useful tool: the information panel. If not, open it from a window and give it a permanent place on your desktop. (Figure 18) No matter what tool you are currently selecting (with the exception of the text tool), place the mouse pointer on the screen, and the color information of the pixel under the pointer will appear in the information panel. Only knowing how to use numbers to adjust color can truly be considered a mastery of color correction. We won’t go into too much detail about numerical values in this article, but this method is very different from other methods. Just remember one fact when you adjust colors: a neutral-colored pixel, its RGB value should be equal. No matter what they are, they are all equal. Color values vary greatly from light gray to dark gray, but if its R=G=B, then it is neutral. Our eyes and brains are highly adaptable and work together to give objects what the brain perceives as black, white or neutral color. Color is easy to estimate from the monitor, but black, white, and especially neutral colors should be determined from the information panel. Sorry! I can’t tell you what color your skin should be, or what values are appropriate for green grass or navy, but neutral colors can serve as your reference point. Of course, not every image has neutral colors in it, but if you take a look, you’d be surprised how many images use neutral reference points: a white shirt, the tires on a truck, a picture on a table Paper, asphalt on a stone pavement, white fence, granite construction…you get the idea, if you need a neutral color the chances of finding it in one object are 100%. So how do you select those pixels with the color shown in the information panel? It’s certainly not a neutral color, the blue value is much smaller than the red and green values. What’s the opposite color of blue? It’s a beautiful yellow. Assuming it is a neutral color, we add blue to the other colors. ◎
When you first see the picture below (Picture 19), you may have a clear impression: there must be something wrong with this picture! This is a picture taken with a digital camera When looking at studio images, we often think of it as the lack of red in the studio lighting, which results in a greenish image. But the combination of light and camera in this case is more yellowish than greenish. How do we know? Well, let’s illustrate by looking at a potentially neutral reference point for an image. Place your mouse pointer over any pixel in the image that you think might be a neutral color, and the information panel once again tells you that blue is severely lacking. Now you understand!◎
It is the reference point I selected (Figure 20) and the information panel display (Figure 21), as well as the corrected image (Figure 22). ◎
I have spent a lot of space describing how to use neutral colors to eliminate color casts, but not all images need to be like this! When the tone of an image needs to be warmer or more You only need to do this when it is cold so that it can better match with other images. For example, you need to add russet to exaggerate the sunset or bright light shining on the lawn. Add a touch of red to the skin of your face or remove some yellow from a dusk photo. It’s no problem for you. Similar to increasing or decreasing contrast, you can do it with curves. Find the source of the problem in the information panel and select the problematic channel in the curve dialog box to quickly eliminate the problem. When you move the mouse from the image window to the curve dialog box, the prompt message in the information panel will disappear. If you change one or more points on the curve, when the mouse returns to the image window, the difference between before and after the change will be displayed in the information bar (Figure 23). Also, as we have said before, you can determine points on the curve by holding down Ctrl and clicking within the image. In color images, this function is more useful: if you are in a monochrome channel, click to place a point. That’s OK; but what if multiple channels need to be placed with multiple points? Repeatedly clicking on the points to be selected in the image window is not a pleasant thing, and it is difficult to ensure that the same point is selected every time. At this time, the color sampler tool hidden under the eyedropper tool can be of great help to you. Click on the image to place a reference point, and the color information of the labeled reference point will appear in the information panel. Now just adjust the curve by referring to the numerical value. ◎
Keep sampling, remember the three eyedropper tools we mentioned earlier? They allow you to set a specific color for the image under the mark. For images with special requirements, this is very useful. For example, if you need the brightness of the image to be in the range of 250, 250, 250 and 5, 5, 5, just set the white and black straws respectively. Combined with the neutral colors we described earlier, you probably already know the grayscale The straw works. Most of the time, I’d rather use a curve, but an eyedropper is also a pretty hand-friendly tool. Sometimes I also use Auto Curve, which makes the darkest pixels black and the brightest pixels white within each channel, which is fine some of the time, but usually it creates strong colors and contrast . The preview window will reflect the changes to you. If you are not satisfied, hold down Alt and “Cancel” will become “Reset”. What is there to worry about now? ◎ We have seen so much about the entire image, but You also sometimes have to look at when curves are applied to local selections. Sometimes the foreground and background colors don’t match, sometimes the background is too dark and the object is just right…many situations must be taken into account. After making all possible adjustments to the image, we can also use the selection tool to select a selection and use curves to make local adjustments. Curves work within selections as well as within channels.
Additional explanation:
The following 4 tips will make your work easier.
1. Fading curve Shortcut key: Shift+Ctrl+F. Sometimes you do a good job, but it seems a bit “over”, and you don’t want to use the Undo command to bury your achievements. In this case, you can use the “Fade” command to lighten the curve effect. As the quantity decreases, the effect becomes less and less obvious. However, remember: fade can only be used after you have just finished using the curve and before using other commands, otherwise your next command will fade
2. Undo and redo If you are not satisfied with the curve effect you just made, you can use Ctrl+Z to eliminate it like other Photoshop commands; you already know the shortcut of the curve command The key is Ctrl+M, but did you know that if you hold down Alt+Ctrl+M, the dialog box will open with the last curve set? This way you can continue to adjust. This is not like method 1, which is a lightening effect based on the original adjustment, but a completely new adjustment. Of course, if you want, you can also make adjustments based on the original. It is not like the fade command, which can only follow the previous command. During the working time of Photoshop, it can remember the position of the last curve. What is its use? If you need to do the same curve processing on 6 more pictures, then you only need to make a curve adjustment once, and then press the shortcut key, and the remaining 5 pictures can be done the same as the first one.Finished. In addition, the level, saturation, and color balance commands can also work in the same way
3. Batch processing If you want to record some representative curve types so that you can apply them to similar pictures next time, then method 2 is helpless. At this time we can use storage command to store an adjusted curve shape in a fixed folder, and then use Photoshop’s Action command to record and load the curve. In this way, you can quickly process a large number of pictures with the same curve. ◎
4. Adjustment layer
This is my last resort. Each new version of Photoshop brings new features that make it easier and easier to use, like the new adjustment layers, which allow you to make unlimited changes to an image without destroying it. Open Layer > New Adjustment Layer, select Curve (Figure 24) (or something else) in the drop-down menu, the layer properties dialog box appears, see the automatically named Curve N, click OK and the previous one will appear. The same curve dialog box, where you can adjust the image. If you are not satisfied, double-click the layer thumbnail and you can continue to adjust based on the previous one, just like method 2 we just mentioned, the difference is , you can adjust the curves at any time before flattening the layers. It won’t damage the actual pixels, so you can use it with confidence. Behind the layer mask, you can protect certain parts from the curves. Don’t forget this tip! The more you change an image, the more you need to keep it as pristine as possible, especially if it’s something bizarre. Let me tell you some personal experience: you only need to perform this little trick once on many layers, and countless magazine covers will go crazy for it! ◎
Special effects
You have mastered the powerful curve function and know what it can do for you, but after saying so much, some people still feel that it is not enough without using curves to create some special effects. Okay, Here I will give you the simplest and most commonly used special effect, which is usually used to express highly reflective materials such as metal and glass. It’s very simple, so I won’t talk nonsense. Basically, it’s blur, then adjust it with curves, and finally use the hue/saturation command to color it, as shown in Figure (25-29). ◎
We know so much about curves that we can basically handle them. To gain more experience, we need to explore by ourselves in practice. Well, I hope this article can be helpful to you! ◎
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