Advice on scanning cover art

Once you get a dark area in a scan to be pure black or a light area to be pure white, other parts of your image are most likely clipping severely. You’re probably not taking it this far, it usually ends up being overly contrasty.

If you’re being more gentle with it you may lose paper texture, noise or detail in some parts of the shadows and highlights, but not everywhere.

In Photoshop’s levels tool you may hold the ALT key pressed while using the sliders to see exactly where the channels are clipping. I found this to be really helpful. Unfortunately Gimp doesn’t have this kind of functionality built in.

Setting shadows and highlights manually so that they’re just about to clip is good practice. You won’t get the blackest blacks and whitest whites this way, but you’re not losing any information either. It keeps the fidelity of your image perfectly intact.

To correct the color manually you could try setting the levels of the individual channels the same way. If the darkest and brightest parts of your image are black and white you should end up with fairly neutral colored shadows and highlights.

If your image is still not contrasty enough at this point, you could use the curves tool to carefully bend the shadows and highlights a little further into saturation without hard clipping anything or messing up the mid tones.

Generally I wouldn’t expect a scan to have perfect blacks and whites. Paper and ink tones are always going to be a little off and uneven. Those are the limitations of the medium. I try to accept them.

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I can’t understand this harsh criticism of jpeg. The size reduction is quite significant, even at high quality levels (where I cannot recognize any artifacts). Instead of switching to lossless, better increase the resolution. This gives a much better quality-per-filesize yield.

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JPEG was designed for photographs, and does actually still do well for that sort of images. It’s much worse when the image includes sharp edges, like pixel art or anything including text and strongly-defined boxes – like, say, an album cover. It still definitely works, but given that we have an alternative with objectively better quality and not too much larger a file size, the only reason to use JPEG would be if we were vey tight on space. We aren’t. The standard line is “The Cover Art Archive hasn’t complained yet”, and if users care for within their own environment, they’ll be using the smaller image sizes (which offer a bigger savings than the different format) anyway. I can definitely see the data-per-byte argument for personal image libraries, but it’s not really important given how much space we have access to.

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Gradients can be quite a problem as well. JPG will turn a smooth gradient into clearly defined bands unless one adds a bit of noise for dithering. That’s why in Photoshop’s gradient tool dither is activated by default.

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  • If there are JPEG artifacts (always talking about high JPEG compression quality), instead of switching to lossless better double the resolution. This will typically result in about the same file size as low resolution lossless, but the information content of the image is much higher (If you don’t believe me: Just try it on you own!)

  • If there are no visible artifacts, you can take the file size reduction of JPEG for free. This typically occurs when the scanning resolution is high enough, above the original printing resolution (which for archival purposes you should do anyway). The reason is that there are no sharp edges any more and JPEG won’t do any harm.

For cover art scans, this typically means:

  • If you do 300 DPI lossless, you really should switch to 600 DPI high quality JPEG. About the same file size, but much better images.
  • If you do 600 DPI lossless or higher, you could just as well go with the file size reduction of JPEG as there won’t be any recognizable artifacts. For the very rare exceptions, 1200 DPI JPEG would again result in much better images than 600 DPI lossless at a similar file size.

For an example, Look at this recent 600 DPI scan @ JPEG qualtiy 90. There are somewhat sharp contrasts at the border and at the logo in the upper right corner. Do you see any artifacts? I do not.

The file size is ~5.5 MB. Lossless PNG would result in ~18 MB, without any recognizable improvement. Lossless PNG at 300 DPI would result in ~5.0 MB, but the original lossy 600 DPI version is much better.

In a nutshell: If there are visible artifacts in high quality JPEG compression, the scanning resolution was not high enough.

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The left edge has artefacts, but it’s not a compression issue. The highlights are clipping there.

I agree that JPG compression is not much of a problem as long as the quality settings are reasonable.

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Thank you for looking at the image. Usually, I’m setting the black and white point such that the image is just about to clip. However, I don’t care for clipping in areas which are clearly supposed to be all white or all black, as in this case the white parts at the border.

Right, you’re only losing noise and paper texture there. And yes, it was meant to be white, but paper just isn’t perfect. I has a bit of a texture, may be uneven or off-white.

Having paper texture and noise throughout the whole image would be preferable to a tiny bit of extra brightness. Blank spots don’t look good in a noisy environment.

Other than that your scan looks pretty good.

I strongly agree about 600dpi being preferable to 300dpi, though I don’t see the problem with jpg artefacts. Moiré is a much bigger issue.

Okay, here’s my first attempt (I scanned, rotated a tiny bit, cropped, and resized):

Outside the Lines

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Looks good to me. Nice definition, no visible defects that I noticed. High resolution for archival quality image.

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I’m definitely in the “You can always reduce, but never restore” camp. :slight_smile:

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These have a lot of clipping.
Clipped highlights:

Clipped shadows:

There prints on the backside of the pages are showing through. You could put a black piece of paper behind the scanned page to avoid this.

When rotating an image I prefer setting the text straight instead of the cover, but that may just be my personal preferance.

As the cover was photocopied rather then offset printed, it is rather easy to deal with. Things get trickier once a screen pattern is in the scan.

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Do you have any advice on how to fix the clipping? I made no color adjustments, so they all came through from the scan itself.

It depends a lot on your scanning software. Most have all kinds of auto adjustments that you could turn off.
If it has some kind of “professional mode”, turn it on. It should give you better control.

If it has levels adjustments with a histogram it’s usually best to set shadows to 0 and highlights to 255 on input and output. The histograms in scan software aren’t all that accurate, so it’s better to set the levels in Gimp and Photoshop where you can see what you’re doing.

So here’s a question, since I’m playing around to see if I can improve these: what do you do about areas that the scanner just doesn’t seem to capture correctly? For instance, in this image you can see a beigy glob of translucent paint, right on top of the O. Well, in real life that spot, and all the other similar spots, are a BRIGHT chartreuse. The image doesn’t look anything like their real color. Any suggestions?

Mine has the same problem with fluro colours as well.
I just assumed that something about the way my scanner works doesn’t reflect those colours properly, which I think is kind of correct:

Your scanner (actually it’s an All-In-One printer/scanner/copier) uses CIS (Contact Image Sensor) instead of CCD (Charge-coupled Device) hardware. With a scanner that uses CIS, the light used to illuminate whatever is being scanned comes from a combination of Red, Green, and Blue LED lights, where a scanner that uses a CCD setup usually uses a fluorescent light.

I would say that the RGB (Red, Green, Blue) LED setup just doesn’t allow the dayglo/neon/fluorescent colors to “shine” (reflect) like they do under other light sources (incandescent, fluorescent, or daylight).

So I’ll hazard a guess that your scanner just won’t be able to accurately reproduce the colors of something with dayglo colors.

There’s a few others discussions on the subject but it looks like everyone just says to either take a photo, or post-process the fluro section (something I do if I have time, otherwise I just leave a comment saying the actual product is brighter)

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A handy tip (unrelated to the above):

I’ve recently started scanning multiple things at once when possible.
eg it’s easy to scan both sides of a cassette in one pass - let the scanner scan the first side, lift up the scanner cover (while it’s still scanning) turn over the cassette and move it down to where the scanner hasn’t reached yet, close lid again.
Or just lots of similar items on the scanning tray at once.

Just thought I’d share.

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Yeah, that’s kinda what I was afraid of. Can you point me to any good resources on post-processing?

When I went to look, there aren’t any prints TO show through, so I’m not sure what you’re seeing? The back of the cover image is blank and I didn’t scan it; the other parts have extra layers of paper between them (sleeve for the CD).

Personally I use Photoshop, select the fluro area with the selection tool (and probably copy it to a new layer so the original is safe), and then simply crank up the saturation. Other image editing software should have similar features.
This is not a perfect solution, it still doesn’t look exactly like the in-hand product - but at least you can tell it’s fluro.

Perhaps taking a high res photo, and then merging the fluro bits with your scan… if you have a good camera and the time and energy.

I actually have a good example of some fluro scans here:
https://beta.musicbrainz.org/release/8b1a0c7d-28cc-4cb0-b357-de865fe8b557/cover-art - this one has a fluro orange post-it note, unedited (very desaturated)
https://beta.musicbrainz.org/release/4ae5f767-e892-49bf-8208-8ee3d7fc6d68/cover-art - this one has a fluro pink post-it note, with the saturation levels turned up. As you can tell, not perfect, but at least it’s pink.

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I have a CCD scanner with LED light source. I don’t think the light is the problem. The scanner will capture the colors in a recognizable way, but they’re clipping in a raw scan without any colormanagemnt. I guess the CCD element can’t capture all their brightness. Maybe the color gamut of CIS elements is even more limited?

Whoops. I misidentified the faint line on top of the page with the line up. Must be just some subtle coloration. Sorry about that!