Various methods of making photo selections in photoshop – skills tutorial

Author: link0 (color friend) Source: China Tutorial Network
First of all, a statement: Most of the methods in this article are not original, but just my study notes.

Due to my limited level, I cannot guarantee that the statements and understandings in this article are completely correct. At the same time, everyone is welcome to criticize and correct me.

Creating precise selections and adjusting only the areas you want to adjust without affecting other areas is an important step in completing post-production adjustments with high quality and efficiency.
Through this period of study, I combined the methods collected from various places with my own understanding to make this simple tutorial. I think this must be what beginners want to know most.
Nowadays, many color correction tutorials include calculations of various channels. Some DX do not explain why. Often beginners are confused and cannot understand and digest well.
Actually Part of the purpose of their calculations is to make selections.
The purpose of making this simple tutorial is to inspire beginners (veterans can just skim it, haha), and at the same time, it can also receive criticism and correction from everyone.
Everyone can feel that they have gained something. , then it would be worthwhile for me to spend several hours organizing the tutorial.

Second method: Common method, CTRL+ALT+~ or CTRL click on the RGB channel to obtain

Obviously, the selection ranges of these two methods of selecting highlights are different. Look at the picture below:

The range of the first method is significantly smaller than the second method. If the second method is used, calculate it again, as shown below

2. How to choose the mid-tone.

The first method: Menu-Image-Calculate the gray and gray reverse channels as shown below, and the blending mode is Multiply. Get the alpha channel.

Second method: Menu-Image-Calculate the gray channel as shown below, and exclude the mixing mode.

3. How to choose dark tones
Menu-Image-Calculation is as shown in the figure below, gray reverse and gray reverse channel calculation, blending mode Multiply. Get alpha channel

Original picture:

Four, how to select colors.
The selection-color range method is more commonly used, but through calculation in the LAB channel, a better selection of commonly used colors can be obtained.

Introduction to LAB in PS: CIE L*a*b* color model (Lab) is based on human perception of color. The values ​​in Lab describe all the colors that a person with normal vision can see
.
Lab is considered device-independent because it describes how a color appears, rather than the amount of a specific colorant required by a device (such as a monitor, desktop printer, or digital camera) to produce the color
color model. Color Color management systems use Lab as a color scale
to convert colors from one color space to another.

The luminance component (L) of the Lab color mode ranges from 0 to 100. In the Adobe Color Picker and Color palette, the range for the a component (green-red axis) and
b component (blue-yellow axis) is +127 to -128.

A channel: dark green-50% gray-bright pink, b channel: bright blue-50% gray-yellow. There is neutral gray in both channels, and we can use this to select the main colors such as green, red, blue, and yellow.
As shown in the figure: Taking channel a as an example, 0 is the middle gray, 0–+127 is the red area, and -128–0 is the green area. By adjusting this part of the curve individually, you can adjust this color.

The following is how to choose colors:
Original picture

First, enter the channel panel, create a new alpha1 channel, and fill it with 50% gray with shift+f5.

[table]

Further strengthen the selection, calculate as shown below, and get the alpha3 channel, which is the desired red selection.

2. How to select green:
Menu-Image-Calculate as shown below to get the alpha4 channel. Initial green constituency was obtained.

Further strengthen the selection, calculate as shown below, and get the alpha5 channel, which is the desired green selection

Search for updates Posts on many related topics: ps theoretical skills photoshop tutorial

Author: link0 (color friend) Source: China Tutorial Network
First of all, a statement: Most of the methods in this article are not original, just my study notes.

Due to my limited level, I cannot guarantee that the statements and understandings in this article are completely correct. At the same time, everyone is welcome to criticize and correct me.

Creating precise selections and adjusting only the areas you want to adjust without affecting other areas is an important step in completing post-production adjustments with high quality and efficiency.
Through this period of study, I combined the methods collected from various places with my own understanding to make this simple tutorial. I think this must be what beginners want to know most.
Nowadays, many color correction tutorials include calculations of various channels. Some DX do not explain why. Often beginners are confused and cannot understand and digest well.
Actually Part of the purpose of their calculations is to make selections.
The purpose of making this simple tutorial is to inspire beginners (veterans can just skim it, haha), and at the same time, it can also receive criticism and correction from everyone.
Everyone can feel that they have gained something. , then it would be worthwhile for me to spend several hours organizing the tutorial.

The second method: common method, CTRL+ALT+~ or CTRL click RGB Channel obtained

It is obvious that the selection ranges of these two methods of selecting highlights are different. . Look at the picture below:

The range of the first method is significantly smaller than the second method. If the second method is used, calculate it again, as shown below

2. How to choose the mid-tone.

The first method: Menu-Image-Calculate the gray and gray reverse channels as shown below, and the blending mode is Multiply. Get the alpha channel.

Second method: Menu-Image-Calculate the gray channel as shown below, and exclude the mixing mode.

3. How to choose dark tones
Menu-Image-Calculation is as shown in the figure below, gray reverse and gray reverse channel calculation, blending mode Multiply. Get alpha channel

Original picture:

Four, how to select colors.
The selection-color range method is more commonly used, but through calculation in the LAB channel, a better selection of commonly used colors can be obtained.

Introduction to LAB in PS: CIE L*a*b* color model (Lab) is based on human perception of color. The values ​​in Lab describe all the colors that a person with normal vision can see
.
Lab is considered device-independent because it describes how a color appears, rather than the amount of a specific colorant required by a device (such as a monitor, desktop printer, or digital camera) to produce the color
color model. Color Color management systems use Lab as a color scale
to convert colors from one color space to another.

The luminance component (L) of the Lab color mode ranges from 0 to 100. In the Adobe Color Picker and Color palette, the range for the a component (green-red axis) and
b component (blue-yellow axis) is +127 to -128.

A channel: dark green-50% gray-bright pink, b channel: bright blue-50% gray-yellow. There is neutral gray in both channels, and we can use this to select the main colors such as green, red, blue, and yellow.
As shown in the figure: Taking channel a as an example, 0 is the middle gray, 0–+127 is the red area, and -128–0 is the green area. By adjusting this part of the curve individually, you can adjust this color.

The following is how to choose colors:
Original picture

First, enter the channel panel, create a new alpha1 channel, and fill it with 50% gray with shift+f5.

[table]

Further strengthen the selection, calculate as shown below, and get the alpha3 channel, which is the desired red selection.

2. How to select green:
Menu-Image-Calculate as shown below to get the alpha4 channel. Initial green constituency was obtained.

Further strengthen the selection, calculate as shown below, and get the alpha5 channel, which is the desired green selection

Search for updates Posts on many related topics: ps theoretical skills photoshop tutorial

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