I am a reletive newcomer to GIMP. I have searched the Manual and the
plugin registry to see if anything like this has already been done, but
without success. So I'm asking if anyone out there can help or point me
in the right direction.
I am in the process of archiving my collection of 300 or so vinyl
records. This includes recording them digitally, filtering out clicks,
rumble, etc. and burning to CD. I am also scanning the covers, labels
and inserts and burning them on a second session of the CD. And so the
whole record and packaging is preserved for posterity.
The average album cover is over 12 inches square while my (average)
scanner can only handel about 8.5 x 11. So each side must be scanned as
four separate quadrants and then be merged back into one image.
I have been using GIMP to reassemble the images with excellent results.
The problem is that it is taking me several days to complete each
images. Do the math, and it will take me several years to complete
this. I'm sure the process could be made faster with a little help from
the experts :-).
Why does it take so long just to load two images, move layer and
-) The layers must line up pixel-perfect. Album covers were printed
with the same technology which prints pictures in the newspaper using
different sized dots of color to create a grayscale. If these tiny dots
don't line up perfectly then you get an interferience pattern visable
from across the room.
-) After 30-40 years, the album covers are no longer square. So the one
image is usually rotated slightly from the other and must be corrected.
It takes me 2-3 tries to get this right.
-) Since the scanner performs a new gamma correction on each scan, one
image is usually lighter than the other and must be brightness/contrast
corrected. It can take a few tries to get this right.
-) Publishers tended to cram the backs of album covers with very fine
text. This means a resolution of 600ppi to adaquately reproduce. At
that resolution the images are quite large and it can take two minutes
for each of the steps above to be performed. And reset. And tried
again. Point is, everything happens real slow. Nothing happens in
The ULTIMATE SOLUTION
I would like to start with a GIMP file containing a background and a
I would like to identify eight pixels within this file:
1) A pixel from the top/left of the background
2) That same pixel from the top/left of the layer
3) A pixel from the bottom/right of the background
4) That same pixel from the bottom/right of the layer
5) A light pixel from the background
6) That same light pixel from the layer
7) A dark pixel from the background
8) That same dark pixel from the layer
I would then like to feed those eight pixel coordinates into a Script-Fu
which would then automaticly perform the translation, rotation, contrast
and brightness corrections. I could then give eyeball approval, flatten
That all being said, what do I need?
1) Has any of this been done already? For example, does anyone know of
a Script-Fu which does the translation/rotation bit and I would only
have to add the contrast calculations to it. It's always easier to edit
than to create :-).
2) How do you get the RGB value of the pixel the cursor is pointing at?
I assume it is possible...
3) Given the last four pixels listed above, just what are the equations
used to calculate the brightness/contrast adjustments needed to
Thanks in advance for all your help.
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