Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Peachpit products and services that can be purchased through this site. Once all these fixes are made, they'll be with you until you change them back. In the current state of technology, it won't affect your conversions between RGB and LAB, but you should change it anyway. Also, Relative Colorimetric is the correct Intent setting for most conversions your system may have Perceptual as the default. So, I'd use Convert to Profile, but I'd turn off the dither, as shown in Figure 3.7. Since we commonly go back and forth between RGB and LAB (and therefore are applying the noise twice), and since there's often a sharpening or contrast enhancement in between that could conceivably aggravate it, I'm a bit leery of putting it in in the first place, although I think it's a healthy thing when going into CMYK. By default, when converting between colorspaces, Photoshop introduces a very fine noise, or randomization, hopefully so fine that nobody can see it, yet sufficient to wipe out any banding or posterization, of which phenomena noise is an enemy. The reason for dropping the dither is philosophical I'm not sure it has any realworld impact. Although Convert to Profile can also be used to go into CMYK, I use a simple Image: Mode>CMYK instead. For converting between RGB and LAB, I prefer to use the Image: Mode>Convert to Profile (Photoshops 6–CS), Edit: Convert to Profile (CS2) command, with Use Dither unchecked.Unless otherwise stated, those acronyms mean the variants thereof specified in Figure 3.6. Otherwise, there will be differences in things like the equivalencies shown in Figure 3.5.Īlso, from here on, I'm not going to waste space with a reminder every time the acronyms RGB and CMYK appear that they permit differences in definition. If you use these RGB and CMYK settings, your Info palette will report numbers similar to those of this book, although certain other settings may cause them to vary slightly. If you are dead set and determined to follow the exact numbers shown here, make your settings match otherwise, leave them alone and you won't miss much.įigure 3.6 This book uses the above definitions of RGB and CMYK in computing color equivalencies. These settings are chosen only because more people use them than anything else, and not because I approve of them, which I do not. However, we have to assume something, and it's going to be what's shown in Figure 3.6. It's off-topic for this book, because it has little impact on the question of when to use LAB. The subject of what definitions to use has generated more heat than its importance merits. Therefore, if we each convert an LAB file to one of the other colorspaces, we'll get different results, unless your workspaces (Edit: Color Settings Photoshop: Color Settings in certain versions) happen to match mine. Our definitions of RGB and CMYK may not be. In Photoshop, LAB has a fixed meaning: your LAB is the same as mine. While on the topic of equivalencies, here's an optional change.Even though I've worked in CMYK for a very long time, the LAB values now make more sense to me-certainly more than RGB! I now have my own Info palette set to LAB on the right, no matter what colorspace I'm working in. You will doubtless think that I should be sent to an asylum for saying this, but after a while the LAB values will start to make more sense than either of the alternatives. Below, left to right: the palette shows RGB equivalents to the current LAB values when a curve is being applied, it shows before and after values, separated by a slash if the value is not reproducible in CMYK, an exclamation point appears after the CMYK numbers to indicate an out-of-gamut color. Figure 3.5 The right half of the Info palette should be set to whichever colorspace you are most familiar with (left).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |