August 24, 2008
One potential issue with some (but not all) RAW processors is that they may apply a saturation algorithm that is prone to making flesh tones appear green.
(click for a larger image)
In the comparison above, the image (the back of my hand) was processed via Adobe Camera RAW and Colormancer (my saturation algorithm). What is [...]
Filed under: Photoshop, color correction, color science | Comments (5)
August 13, 2008
Is there such thing as perfect white balance? Some people worry over getting white balance technically correct. And there are products on the market such as Expodisc that try to do exactly this. In my opinion however, you don’t need to obsess over white balance. Why? Because our perception of color is a guess to [...]
Filed under: color correction, color science, still photography | Comments (6)
June 28, 2008
Illusion: In your peripheral vision, you may see dark spots where the lines intersect. If you look at an intersection directly, you can see that there is actually no dark spot.
The textbook explanation for this effect has to do with the ganglion cells in our eyes. In the center area of our [...]
Filed under: color science, visual illusions | Comments (0)
June 23, 2008
Color spaces can generally be classified as chromaticity or chrominance based. Both are different styles of defining color. Chromaticity is “color” defined independent of luminance (or the equivalent of luminance in a particular color space). Suppose you used a neutral density filter on a camera or changed the intensity of the lighting. The [...]
Filed under: color correction, color science | Comments (5)
June 23, 2008
For color correction, it might seem sensible to use a perceptually uniform color space. CIE L*a*b* is one such color space that is designed to be perceptually uniform.
In the context of LAB, perceptual uniformity means that the ability to tell two shades apart is uniform. This is usually measured in just [...]
Filed under: color correction, color science | Comments (3)
June 23, 2008
One area where surround effects make a big difference is when evaluating the black level on LCD monitors. Almost all LCD monitors cannot reproduce true black and have a raised black level. In a dark room, they will have a “glow in the dark” appearance to them. The image below shows the [...]
Filed under: color science, monitoring, visual illusions | Comments (0)
June 22, 2008
One of the factors that affect the perception of an image is the content of the area surrounding it. In the example below, the center patches of the color have the same value (128 128 128 RGB) yet the left patch appears to be lighter than the one on the right.
Adding [...]
Filed under: color science, monitoring, visual illusions | Comments (1)
A blog by Glenn Chan. Check out Free Photoshop Plugins and my commercial color correction Photoshop plugins (Colormancer) for information on my plugins / filters.
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