Advice on scanning cover art

[spitzwegerich]

@WovenTales

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.

• 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.