Photoshop: Do I really need it and why?

[Carnifex]

Ok. Now I have tried out GIMP trying to find out the differences between Photoshop and GIMP. This post is a mix of my opinions and what I think is fact

GIMP
GIMP is a nice program. It's free and has alot of nice tools for working with images. Most of those tools work as in Photoshop. I recommend it if you don't have the money to spend on Photoshop. GIMP is easy to use - easier than Photoshop. Some major drawbacks include good support for CMYK and the advanced user will miss many many tools from Photoshop.
PRO: Free and easy to use
CON: Not made for printing

Photoshop<RGB vs CMYK
First I will say that i will not try to explain the quite complicated matters of RGB vs CMYK.
1. You cannot print in RGB directly - this is an absolute fact. Most print shops (99%?) work in CMYK to print colour images - CMYK. (If you have a printer at home they might use more than 4 colours to create better, richer colours.)
2. While you certainly could work in RGB the result on paper will be different. As RGB can represent more colours than CMYK (but not all) most CMYK colours can be watched on a computer screen.
A Quite Nice Summary From Wikipedia:
"While processing a digital image, the most convenient color model used is the RGB model. Printing the image requires transforming the image from the original RGB color space to the printer's CMYK color space. During this process, the colors from the RGB which are out of gamut must be somehow converted to approximate values within the CMYK space gamut. Simply trimming only the colors which are out of gamut to the closest colors in the destination space would burn the image. There are several algorithms approximating this transformation, but none of them can be truly perfect, since those colors are simply out of the target device's capabilities. This is why identifying the colors in an image which are out of gamut in the target color space as soon as possible during processing is critical for the quality of the final product."

Here's some info from Wikipedia:
http://en.wikipedia.org/wiki/RGB
http://en.wikipedia.org/wiki/CMYK
http://en.wikipedia.org/wiki/Gamut

/Claes

(Note: I don't know everything but I have worked a long time in the graphic business - 3 years in a print shop doing prepress work, 7 years as a graphic designer and art director, and the last 2 years I have worked as a teacher in Photoshop and InDesign etc.)

[Seamus]

Thanks for the advice guys. My only color image is the cover art and logo. Everything else will be black and white. What should I do to ensure best results on the cover image if I only have GIMP and INdesign? (we will be using Lightning Source for most of our printing if that makes a difference). I don't know what the colors will be, but believe it is going to be an orange/red theme.,

[Ben Lehman]

Use file->place to place the images into InDesign. As long as the graphics files aren't screwy in some way, that should work fine.

yrs--
--Ben

[greyorm]

Thanks for the advice guys. My only color image is the cover art and logo. Everything else will be black and white. What should I do to ensure best results on the cover image if I only have GIMP and INdesign? (we will be using Lightning Source for most of our printing if that makes a difference). I don't know what the colors will be, but believe it is going to be an orange/red theme.

Note: IME oranges and reds look brighter on the screen than they ever do in print. You should be able to get them close, but keep that in mind.

First, always follow your printer's instructions for size, bit-depth, bleed, color mode, and so forth.

Second, the answer depends on whether you are creating the cover yourself, or have an artist creating it for you.

If the latter, it is (or should be) part of his job to make sure the cover art is print ready, meaning you should receive the piece already prepared and proofed in CMYK mode and your job will be to drop it into INdesign. However, if he doesn't do this, and your printer requires a CMYK file, then you will need to convert it yourself via GIMP and check it.

If the former, and I can't emphasize this part enough: Calibrate your monitor first. There are numerous free tools and sites on the web that can help you with this. Find one that works for you (Google "monitor calibration" and start reading). Then make sure the image is in CMYK mode to get an idea of what the cover will look like, also printing a copy on your home printer or down at the local print shop to see the "actual" output.

Always get a proof from your printer -- it's the only way to tell what their press is going to do with the image (every machine produces slightly different results -- one extreme example: when I was with the resort. We outsourced a run of brochures to a local print company instead of our regular printer, and despite our screen and our own proofs having rich blue water--and our regular printer's output of the same product matching ours--the local printer's proofs came back with the water tinged a ghastly purple).

(I have no experience with LS, so I don't know if they send you a proof or not as part of their process, or if you'll simply need to order a copy to see what their presses do with it ala Lulu.)