Digitizing traditional art

[mekare]

Hey, I hope some of the graphics programme users here can help me. I have finished a big watercolour piece today and tried to scan it in two parts. Now my idea was to merge those two parts in a graphics programme. Has anyone ever done it successfully? I only own a freeware programme (GIMP) which is supposed to be similar to Photoshop and there was definite line separating the two scans. Any idea on how to get rid of it or a better method? I tried taking photos of the whole picture but they came out much darker than the scan (I adjusted brightness and contrast of the photo in that same programme but it's still not as light as the scan).

ETA: Thank you everyone for all the helpful tips. I'll definitely try the overlaying this weekend with an additional middle part scan. I knew I could count on you :-)

ETA2: I think I did it! I put two scans together and adjusted the brightness of the lighter one, scaled down the resolution somewhat and now the line is almost unnoticeable. Thank you all! Unfortunately I can't post the result yet, since it is a Bigbang piece, but I'll post a link when I'm allowed.

Comments

[ratcreature]

I have done this with GIMP for larger acrylics paintings several times (examples: here, here, here) and fairly successfully, though it is hard to get rid of a line entirely.

In my experience there is no special trick just tedious fiddling. And the main thing is to post at a screen resolution that is significantly lower than the scan resolution so that this will make the border less prominent.

The most important thing when scanning is to scan with a good overlap, because at the border of the scanner there will be distortion, especially if the paper is larger than the scanning surface. Then you align the two parts by overlaying the overlap with two layers, sometimes you need to rotate a fraction of a degree and such to make things line up, then make sure to get the best color match by fiddling with brightness an color curves if the colors that ought to be the same don't match in the overlap. Then I cut of the distorted parts, and then look which part looks better on top. You can try various overlay modes to merge, but I didn't have much luck with that. The main improvement really comes from viewing it smaller.

[alias_sqbr]

ratcreature gave the most important advice, but the simple trick to get rid of an obvious line between two versions that allllmost match is to soften the edge with a gradient mask http://geekswithblogs.net/TimH/archive/2009/03/10/how-to-fade-image-layers-using-gimp-gradientblend-tool.aspx

This will only work on the section where the two images overlap. A bigger overlap lets you do a more subtle fade.

[malnpudl]

Alternative in case this turns out to be problematic: Staples has a great big flatbed scanner and will scan whatever you like for a very modest fee. I'm sure any similar business could do the same.

[darthneko]

My trick for that is to make sure you have at least 2-3" of overlap where the halves of the picture join up. Layer them together, line them up, do whatever brightness and color corrections you need, then GENTLY erase out where the overlap is on the top layer. Use a big, soft edged, low opacity eraser and just erase the top layer portion that overlaps the lower layer to create a diffused join instead of a hard line.

[goss]

The most important thing when scanning is to scan with a good overlap

Agreeing with all the above comments.

What I usually do is scan each half of the page, but then I also scan the exact center, that way I have a HUGE overlap on either side.

I then use the Photoshop erase tool with soft edges in order to make a seamless merging of the three images.

[mekare]

Great idea! If I can't manage I'll go to my local copyshop. I know for certain they have a big scanner (never would have come up with that idea myself though.)

[mekare]

I am currently right in the middle of the tedious fiddling. Thanks for your advice!

[mekare]

Hey, I tried the tutorial but somehow it only worked for things I drew wiht brushes in gimp, but not for the imported images. No idea why. It probably has something to do with layers (which I've never used).

[mekare]

I tried the eraser but somehow I fudged the definition of layers and it didn't work. I really need to do a basic gimp tutorial at some point. I found another solution (see my ETA2 up in the post). Thanks for your help.

[alias_sqbr]

Ah, yeah, this sort of thing definitely requires layers! And I find GIMP layers bizarrely confusing, even though I'm perfectly happy using them in other art programs, which is why I linked to a tutorial (that I haven't tested myself so it may have issues I'm not noticing)