Sorting for high quality cover images

Early in my LT membership I uploaded a lot of rather low quality images. I would like to improve them. It would be helpful if I could sort a list of 'not-high-quality covers', as with Amazon covers, etc.

This would be very helpful.

Of course, it would also be helpful if the current divisions really worked. Most of my 'Amazon images' have long since been changed to default cover.

I recently discovered that if you change an Amazon cover to your chosen default cover, it stays marked as an Amazon cover. If, however, you change it to another default cover (one that isn't your default), it stops being Amazon and turns into Blank cover chosen by you. Which is truly weird, but if you want your stats to make more sense does give you a workaround.

And yes, it would be wonderful to be able to sort/search by quality of cover. I note, however, that some very 'high-quality' - ie, lots of pixels - covers really look awful - the 1000+ high ones seem to resize rather badly (lumpy!).

Something I've been wondering about ... why are there so many blurry uploaded covers? What kind of scanner gives that result? (My scanner is pretty old, and if/when I need to replace it, I want to know how to avoid whatever kind produces the blurs.)

It's not, or mostly not, blurry scans - what it is is very small (low pixel-per-inch) pictures. Many of them are actually thumbnails from elsewhere on the web - when they're only 16 or 24 pixels across, upsizing them to 100 or 250 (250 is the biggest covers on LT - largest size in cover view) pixels is going to produce a blurry image. Even 100 pixels will look pretty bad upsized. If, on the other hand, you scan a cover at 300 or 150 pixels per inch and send it to LT as anything from 150 to 600 pixels high (for whatever reason, I tend to calculate with height rather than width), it will look good at thumbnail to 250 px sizes. Some people send much bigger covers - 1000+ pixels high - but I find that they sometimes resize blurry as well, particularly in the thumbnail. It looks lumpy, somehow.

Any scanner you can buy now will produce very nice scans - will produce good scans that you could blow up to 8x10 if not poster-sized, for that matter. It's more a matter of finding what settings, for your scanner and software, will produce a nice clear image at the sizes LT uses. And that's really cut-and-try - the above info usually works for me, but not always. For some covers I have to scan higher or lower DPI, or resize differently before I upload, to get a good image on LT.

I usually have my scanner set to 96 dpi and I have been happy with the results.

The waviness sounds like Moiré pattern. You get this when you scan a litho printed picture because the colour plates consists of lines of dots of colour each of the four at a different angle. My scanning software (Epson) has an option to select called descreening which prevents this effect. I expect other brands have a similar option.

DPI doesn't really affect much. What's of interest is the actual pixel size of the image. Choose a DPI setting that will give you a large enough image that you can resize down to something reasonable, in whatever image editing program that you use to crop and straighten the image. The LibraryThing website currently doesn't display more than 250x250 pixels (last time I checked); if your image is smaller than that, it will need to be enlarged and look bad if you're displaying cover view at largest size. If your image is much larger than that you're wasting disk space and uploading time, to not much benefit. That said, I scan very large and resize down to 1024 pixels in the largest dimension -- in case some day the site does display larger images.

My HP scanner software also has a descreen option which does a great job of removing the Moiré pattern. If yours doesn't, I've also found that scanning at least twice the size you want and resizing down can also pretty much eliminate it.

7> Are you actually seeing the waves (moiré pattern) in the final scaled down image, or just in your scanning application like photoshop? Because another source of them is when you have a larger image and it's just zoomed out to fit on the screen in your program. If you zoom in, those patterns will go away. It's just a side-effect of it using a faster method to draw the zoomed-out image on the screen. If you actually resize the image (using the menu option, not just dragging the window to make it smaller or zooming out), those patterns will go away. At least, that's my experience using photoshop.

Thanks very much for the answers.

I'm not very good (to put it mildly) at the tech stuff. The default resolution (that's dpi, right?) for my software is 200. I resize to 50%. Seems to work well in most cases.

Glad to learn the cure for that wavy pattern!

Re. #13: "(that's dpi, right?)"

DPI = Dots Per Inch

DPI is the size of the dots involved in various renderings. For instance, the "standard" DPI for the vast majority of computer monitors is 96 ... which is why that was a recommended setting further up the thread.

However, 96dpi will look not-so-good in print ... a standard for most printing is 300dpi (laser printers, etc.), going on up to 1200dpi (and, I assume, beyond, these days) for images to show up in high-quality print contexts.

Most of the images that I upload are 96dpi and 300x450 pixels (for a standard 6x9" book cover), which, for the web, is more than adequate and keeps the files at a rather minimal 300kb-ish size. Obviously, were you intending on having these images for print purposes, you'd want them larger (my original scans are like 2mb large and somewhere around 2500px high).

 

At 96dpi, 300x450 is 3.125" x 4.6875". A 6"x9" image at 300x450 pixels is about 50dpi. But unless you know how may dpi my monitor is, there's no knowing what size a 300x450 image is going to appear, and anyway the site is going to resize it. And who really cares?

300x450 is a perfectly adequate size for display on LibraryThing, dpi is irrelevant.

Just got that wavy pattern when scanning a book, and tried descreen. Wow. Thank you, CDVicarage!

Bumping - with the new work that's been and being done on covers, it would be very nice to be able to identify my poor quality covers to re-scan and upload.

I'd be happy to see it as an addition to the http://www.librarything.com/profile/MEMBERNAME/stats/covers page.

Well bumped.

Agreed, r.orrison. That would be really helpful.

And here it is!

http://www.librarything.com/topic/138204