Adobe Photoshop 7 Tutorials
Color Modes / Index Color
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Subtitles of the Movie (Adobe Photoshop 7 / Color Modes / Index Color)
One option you have with a full-color image is to convert it into an index colored image, under image menu>mode choose index color. So what is going on here is that Photoshop is going to force any pixel into, in this case, one of 256 colors. And the resulting image size will be much smaller, because we won't be working with 3 channels worth of image data, just no more than one channel, and maybe even less than 256 colors which is an option. If I select my color section, I could just type in say 20 and notice what Photoshop is doing. Since I have preview enabled, my image is beginning to degrade a bit not looking quite like a continuous tone image, but generally good enough to get the idea across that this is a dandelion. From the palette pull down menu, we have a handful of options. We could choose from different types of standardized palettes such as the basic web palette, and you can see that if we choose web palette that web palette has 216 colors in it. Could choose from the windows system palette of colors or the Mac palette of colors. Or we could derive the colors based on the colors in the actual document. And that would be one of these three options here. And these will generally create the most pleasing overall effect for index color. If you choose something like the local perceptual type of color palette, we could then go into our colors section here and type in how many colors any one pixel could possibly be. So if I just chose a very low number such as 10, we would have a very small file indeed. Forced allows you to choose if you want certain colors to be forced into the collection of colors. So, we can add black and white so that some of these pixels will have to be black and white, or some of the pixels will be primary colors, or web. And if you choose web of course, it's going to bump up our values for colors to 216. And if you choose custom, it will ask you to go find a palette that you might have saved out. We have a handful of options for how we might want our colors to be dithered. If you choose none, it will create kind of a blocky effect. Or we could create a diffusion dither option, which creates a nice type of effect. And if you choose one of these dithering options, we can add the value of dithering. A lower value will create more of a blocky effect. But also, the lower the diffusion dithering amount, the smaller the file size. So you might want to experiment with different types of dithers and dithering amounts. So I'm going to choose the local perceptual type of palette with 20 colors, and a diffusion dither of about 20%. Notice now how big my image is: 182 kilobytes versus my full RGB image, which is 547 kilobytes. So we've reduced the file size quite a lot, while maintaining the basic look of my dandelion.
Tutorial Information
| Course: | Adobe Photoshop 7 |
| Author: | Andrew J. Hathaway |
| SKU: | 33329 |
| ISBN: | 1889347272 |
| Release Date: | 2002-09-05 |
| Duration: | 11 hrs / 152 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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