Anyone knows the algorithm of PhotoShop's autocolor function?

Question

0.00/5 (No votes)

See more:

Hello, Everyone

Since photoshop 7, ps has three useful function, autolevel, autoContrast and autocolor.

From my experiment, I know that autolevel is just to do autogradation on RGB channels separately. While autocontrast is adjusting RGB channels together based on the autogradation results of gray channel.

But for autocolor, I haven't found the answer. Anyone knowns the algorihm of autocolor?

Posted 8-Sep-11 16:00pm

tank0

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Mehdi Gholam · Accepted Answer · 2011-09-08T16:23:00

AUTO TONE from the manual:
The Auto option for Levels and Curves and the Auto Tone command automatically adjust the black point and white point in an image. This clips a portion of the shadows and highlights in each channel and maps the lightest and darkest pixels in each color channel to pure white and pure black. The intermediate pixel values are redistributed proportionately. As a result, using the Auto option or Auto Tone increases the contrast in an image because the pixel values are expanded. Because the Auto option and Auto Tone adjust each color channel individually, it may remove color or introduce color casts.

AUTO CONTRAST from the manual:
The Auto Contrast command adjusts image contrast automatically. Because Auto Contrast does not adjust channels individually, it does not introduce or remove color casts. It clips the shadow and highlight values in an image and then maps the remaining lightest and darkest pixels in the image to pure white and pure black . This makes the highlights appear lighter and shadows appear darker.

AUTO COLOR from the manual:
Auto Color adjusts the contrast and color of an image by searching the image to identify shadows, midtones, and highlights. By default, Auto Color neutralizes the midtones using a target color of RGB 128 gray and clips the shadowand highlight pixels by 0.5%. You can change these defaults in the Auto Color Correction Options dialog box.