Here’s the second venture, with a more typical cover: https://beta.musicbrainz.org/release/f8895c5c-f194-4880-85bf-fc9ba9ebe7dd/open_edits
I did the same thing, just scan, rotate as necessary, resize. I followed @ZincRider’s advice on turning off the histogram. I imagine some of the previous comments relate to getting rid of the patterns that are showing up in the image, even at “real life” size? I wouldn’t mind doing something about that, too.
You might get some ideas from the tutorials on Fanart.tv. They have some pretty high standards for image quality for uploads they accept, and the tutorials are pretty good. They have a whole series related to image processing with Gimp. You can find them at https://fanart.tv/tutorials/.
Thanks, I’ll check that out.
I just tried it out again. I’m afraid Gimp’s interpolation algorithms don’t seem to handle screen patterns as smoothly as Photoshop’s. 
The easiest way to deal with this problem is to not scale down from 600dpi/actual size.
The other option is to use a FFT Plugin (http://registry.gimp.org/node/19596) for Gimp to descreen before scaling down:
https://www.youtube.com/watch?v=3137dDa6P4s
The video uses a different plugin, but it works in exactly the same way.
Here’s a neat little trick I use to speed up the process: Instead of painting out all the “stars” (except for the one in the center - that one must stay intact) by hand I simply use the elliptical marquee tool to make a selection around the center star, invert the selection (selection->invert) and then apply a heavy gaussian blur. If the image has too many artefacts after applying inverse FFT, I undo everything and start from the beginning with a slightly bigger selection.
The good news is that your new scan is not suffering from blown out shadows and highlights like your last one did.
Don’t be afraid to use the levels tool in Gimp. You’ve protected the shadows and highlights during the scan so now you have something to work with using a tool that lets you do a better job.
I’d certainly bring up the shadows a bit, setting the slider to where something is about to happen in the historgram:
In Photoshop, where I have better visual control over what I’m doing, I’d also clip the highlights so that the white scanner background gets blown out, but the whites in the cover don’t. In Gimp I’d leave them alone, just to be safe.
I scan at 1200dpi, use a photoshop-plugin for descreening [1] only on the parts that have a halftone pattern, crop and rotate, adjust (with curves) the blackpoint until it starts clippin (hold the ALT key while dragging the marker to switch the display to only show clipped areas) and the whitepoint (where I sometimes clip a bit to get rid of shine through or paper that got grey/colorized over the time), then resample to 300dpi and save as png.
this plugin i use (sattva) produced the best results a few years ago, when I tried out a bunch of methods for descreening. If anybody knows a better one, please share. I especially would love a plugin that can deal not only with screened material but detects or has a way to define Spot colors and areas that are not screened, thus leaving them untouched and more crispy.
[1] http://www.descreen.net/eng/soft/descreen/descreen.htm
Concerning descreening: Just stay at 600 dpi (or higher). No need to alter anything. Remember that we are archiving things.
What kind of file sizes are you typically getting? I’m scanning at 600 dpi (and keeping that resolution) and saving as PNG. For one or two panel scans (e.g.: front and back covers on a CD booklet), I’m seeing files from 2 to 20 MB depending on the images. On some stitched fold out booklets (6 panels), I’m seeing close to 50 MB. They are uploading okay to CAA, but it’s taking sometimes 5 to 7 days for the 250px and 500px thumbnail images to be generated so they display on MB. I know people keep saying to keep going until CAA complains, but I can’t help thinking that I should be backing off the detail a little even though it’s for the archive.
Thanks.
Silverfast also has fully automatic fourier based descreening and has a mode that retains text: SilverFast’s Descreening feature removes printing screen and moiré effects
I have no experience with it, though. I mostly use the descreen.net plugin and really love it. Totally worth the money, I can’t recommend it enough. It has saved me dozens of hours of time already.
at 600dpi and saving as jpg I get around 9MB for a CD front, around 18MB for a vinyl single and around 60MB for a vinyl album.
In the past I’ve only uploaded 1080x1080px jpgs, which are around 1MB.
Just so I understand, are you now uploading the larger files, or still limiting to the 1080 x 1080 px? If you’re now uploading the larger files, then it sounds like my file sizes aren’t really out of line.
Thank you all! I found one more “color management” setting in the scanner to turn off (my gosh there are a lot of those!), and played around with the descreen plugin for Gimp and ended up with a result that I am MUCH happier with. Look at the difference (I’ll cancel the first upload, just left it for comparison for the moment):
I have uploaded many 100MB + pictures, mainly stitched ones.
Archive hasn’t complained yet, so I haven’t worried about it. They/we can always downscale it later or implement rules if they want.
As written earlier, at 600 dpi it’s perfectly ok to use jpeg compression for the final image at a high quality level. I go with quality 90 in gimp and I never realized any artifacts. This usually gives me 7-8 MB for a front cover image. This is still a reasonable size in my opinion. The How to add cover art states that “more than 15 MB might be somewhat overkill”, and I think this is a reasonable limit (for images of CD front cover size).
What I don’t like about the howto is the statement “if you’re planning to scan your releases, we recommend doing it at 300dpi”. As discussed, 300 dpi is not enough, but 600 usually is. 600 dpi (or higher) solves so many problems, no descreening needed, jpeg compression for free.
[quote=“spitzwegerich, post:52, topic:260843”]
The How to add cover art states[/quote]
Just a reminder that that’s not an official guideline.
Plenty of people might want you to upload smaller files, for whatever reason, and I’m not saying those reasons are wrong or that you shouldn’t listen, but if you then still want to upload big files, please yourself.
Nice! That’s rather impressive considering you only just started out with descreening. I know it can be rather tricky and many people never get it right…
Thanks! Really, credit goes to the plugin (which piggy backs on the Fourier plugin) and a guide I found for tweaking it.
Plugin: http://registry.gimp.org/node/24411
Guide: http://www.zoyinc.com/?p=1529
I had to do undo part b of the tweaks because it caused an error, but otherwise it did good. I ended up using 50 for sensitivity and 7 for “ratio for middle preservation”. No despeckle.
I found the script really hard to set intuitively, but it obviously works for you. That’s great!
well I think you are fundamentally wrong. why would you archive artifacts that are induced by the production method? more than that it will lead to moire patterns when resized, and it will be resized because you probably won’t have a 600dpi screen.
Am I really confused? Once I’ve done the scan, I can change the dpi all day and it has no effect on the image quality on-screen. The only thing that affects that is the dimension in pixels. Dpi matters for scanning and printing.
you are not confused, dpi matters only for scanning/printing. however if you are scanning the screen pattern (the CMYK dots of the printing press) and don’t “undo” the rasterising process the printing press added you generate moireé patterns if the image is resized (the more primitive the resizing algorithm the worse).
If I am talking about changing the dpi after scanning I retain the physical dimensions of the scanned image therefor resampling the image. so a 12x12cm front cover image at 600dpi resulting in ~2800x2800px will be 1400x1400px at 300 dpi and still have the same physical size after printing.
For anybody else who comes across this and wants to do descreening with this plugin: if you need to descreen just part of the scan, create a new layer “from visible” and crop out everything you don’t want to descreen, then descreen just that layer. (And if there’s more than one section, you’ll get better results if you do each one separately.)
I wrestled with this one for quite a while before I figured out how to make it work. The text showing through from the other pages confused the algorithms and created stripes across the whole image, and for whatever reason you can’t just descreen a selection. You end up with a big blur of nothing.
Added: I’m starting to think the first one turning out so well was beginner’s luck. To get this one to come out decently I ended up descreening the back separately from the spines, and not descreening the barcode at all because having it there threw other parts out of whack. I’ve fiddled with the settings on the plugin a lot, but it seems like what you descreen has more impact on the result than the settings. I’ve still ended up using 50/16/7 for everything.
Also, there’s a good explanation of what the settings mean, here.
