There is some documentation at:

http://www.gimp.org/docs/

And a list of books in print at:

http://www.gimp.org/books/

I have done most of the image processing on the Beatrix Potter books (Not all, but most of them), and while I'm not 100% happy with them, they are fairly decent. For an example:

http://www.gutenberg.org/files/17089/17089-h/17089-h.htm

My workflow for the potter books (color, screened images):
(Note, this also assumes that you are working within the DP workflow; not everyone chooses to do so.)

1) Scan at 600 DPI 24-bit color, using a scanner profile, and not auto-exposure. (Auto-exposure was causing some hard-to-track-down color shifts.) I have calibrated my scanner with a standard target, but the bigger issue is to get the scans consistent across the whole scan. A rough calibration of your monitor settings is not a bad idea, either. There are a number of websites with color bars to assist this.
2) Load two or three images into Gimp/Photoshop, and play with the settings for that particular book.. radius for gaussian blur in the descreening process, levels, unsharp settings, etc. After determining the settings, I'll load them into an action and apply them to all images.

a) Descreen. There are some alternative methods (the russian descreening plugin is pretty good at preserving detail), and some scanner drivers do better than others when descreening at stage 1. Typically, if descreening in software, I'll magnify to 200%, and adjust the gaussian blur radius to just show a slight visible hatching in darker areas.
b) Downscale (bicubic) to 300 DPI. This reduces file size and makes image easier to work with, now that we have removed any possibility of moire patterns. (Staying at 600 DPI does not help as we threw away any extra information with the blur.)
c) Adjust levels, hue, and saturation. It is best done with a light hand, as it is difficult to tell exactly how the colors looked before they faded. Typically I'll show a sample to a few people as a sanity check at this stage.
d) If I don't think the post processor will do one after the final scaling, I will do a moderate sharpening (usually unsharp mask) at this stage to compensate for the blurring effect from  steps b and a.

(These steps can't be scripted and have to be done to each image by hand.)

e) Clean up dust marks, printing artifacts, etc. I haven't found anything particularly effective at repairing misaligned screens (it is usually not visible at the final resolution in any case), but most other problems can be cleaned up.
f) Crop, and force remaining background (if any) to white. Remember, your image will be rectangular and displayed against a white background. You can specify an alpha layer in your PNG, but this will not be preserved in the final JPG.

g) Save as PNG. At this stage, images will be on the order of 1 MB apiece.

I'd prefer to save the raw scans as well, but they are much bigger.

The post processor downloads these images, scales them to fit current guidelines (usually 400-600 pixels across), compresses them to an appropriate format (usually JPG for these types of images), and inserts them into the HTML. Most images end up in the 50-100 kb range.

R C

On 7/9/06, Jacqulyn Perry <urbangleaner56@yahoo.com> wrote:
Oh good!  Does the GIMP software have a Help file? I hope?
 
Okay, what is DP? Is it part of PG?  I'm really interested in working with childrens book illus, as that is what I have some background in as an artist. After I've learned more about working with computer graphics programs, I would probably be willing to help out with the other types of imaging work as well.
Leigh

Juliet Sutherland <vze3rknp@verizon.net> wrote:
Hi Jacqulyn,

You might have a look at The GIMP, which does almost everything
photoshop does and is free.

There is an Illustrators team at DP that always needs help. I hope that
you, and perhaps some of the folks you are in contact with, will join
and give us a hand with our illustrations. I hope that eventually DP
will have a parallel process that will have experts preparing
illustrations while the text is being proofed and formatted.

Whether for DP or otherwise, there are several common steps in prepping
illustrations for a PG book. First, the originals have to be scanned.
Getting good scans of illustrations takes practice and not all of our
volunteer content providers are good at it. But everyone does the best
they can and we encourage them all to scan illustrations at a decent
resolution and, in the case of DP, upload those scans to our server.
Another stage of the process is taking the raw scans and making them as
good as possible, while still leaving them large for archiving. I
usually do this before I upload to the DP server (stuff like deskewing,
making sure the colors match as best as possible, etc). But not all
volunteers have learned enough about graphics programs to do that part.
Then further, PG usually wants illustrations that will look good on a
screen, and to keep the overall file sizes down, so there is another
stage of processing that reduces the image as much as possible without
unacceptable loss of detail. There are definitely tricks to doing that
(which I don't know). Often folks will choose to make a smaller version
for display within the ebook and a larger one that can be obtained by
clicking on the picture. Also, what's considered "reasonable" for size
and detail depends to some extent on the book. A children's picture
book, or a book about art, can reasonably have larger illustrations than
something that was starting with not-so-good B&W photographs poorly printed.

We deal with everything from simple line art to steel-cut engravings
(very fine detail) to printed color illustrations (needing descreening)
to the xyz-gravure stuff that seems to scan beautifully (I don't know
what the process is for the various -gravure stuff but it doesn't seem
to result in the same kind of screen dots that one sees in most color or
B&W photo stuff), to beat-up decorative book covers. There are also
illustrations and maps that are too large to be scanned in one piece and
need to be put back together. Lots of challenges for people who like to
do restoration.

JulietS
DP Site Admin


Jacqulyn Perry wrote:

> My real interest is in working with the images. My problem is I'm not
> very computer literate-I'm an 'old fashion' painter-so I'm not sure
> how much I can do with the limited graphics programs I have.
>
> I'm pretty sure I can take care of the smudge, but it would require me
> using Paint to remove the smudge, then printing the image out and
> doing the retouch by hand-I used to work as a photo re-touch
> person-then scanning the re-touched image to send back to you. Which I
> would be glad to do.
>
> I've posted the image at an artist website I belong to, that has a
> VERY active computer graphics forum and asked their advice. I've also
> asked about a good graphics program. Though from what I've seen so
> far, most of the images you folks have, at the most just require a
> little brightening and maybe a tiny bite of color adjustment. That I
> CAN do with what I have. Anything I CAN'T do, I will say so.
>
> I'm sure that Adobe Photoshop would take care of anything at all I
> would need to do, but due to lack of cash, buying it is out of the
> question for now.
>
> Oh yes, I figured I would need to contact the person who originally
> did the book, and ask for a high res file of the images. I just wanted
> someone to see what a difference lightening them, makes.
>
> Leigh


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