Scanning Auction Catalog Plates
tradedollarnut
Posts: 20,162 ✭✭✭✭✭
Is there a trick to scanning auction plates?? I seem to get an interference in the picture that I can't get rid of - even on large size pictures in the catolog. Any suggestions?
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rainbowroosie April 1, 2003
The photos are 'screened' - reduced to an array of dots for purposes of printing.
Normal is about 60 dpi. There are some ways around it - none eliminate it totally.
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<< <i>4082 posts since December?? Jr, you need to get a life!!!!!!! >>
There is a whole worse things he could be doing. I know alot of parents who wish their 18 year old was
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This is quite true, and it can result in a very grainy scan, especially in enlargements.
In putting together some publications, I've needed to create some scans of auction photos, and I've found a process that seems to work reasonably well for me:
1) First, if a coin has had several different auction appearances to choose from, choose the one with the largest and/or best quality image. Some lots get plated in enlarged color photos and others are only plated life-size. However, some of the enlargements are "screened" more coarsely, so they end up scanning worse than the life-size images. In general, the really "glossy" plates appearing in some catalogs tend to have the best resolution/least grainy appearance.
2) Even though you have a target image size (say at 72 dpi for internet posting) you get better results doing the original scan at higher resolution, and then using image editing software to reduce the resolution. When I'm working to create a scan that will look good for enlarged re-prints, I scan at 1200 dpi.
3) Then, BEFORE using the editing software to resize the image to a lower resolution, use the "remove dust" feature (or the equivalent function in your software), and that works to get rid of most of the graininess. When this is done on a high-resolution scan, the graininess seems to disappear, leaving a clear image. For a lower-resolution scan, the image can end up looking out of focus.
Here are images from two separate scans of the Floyd Starr 1852 Dollar (from the 1982 Stack's sale). Both images have been adjusted to the same final size and resolution (8" wide @72 dpi), and both have been saved at the same level of jpeg compression to fit within the 50K forum attachment file size limit. The first was initially scanned at 300 dpi and the second at 1200 dpi.
300 dpi scan:
1200 dpi scan:
Notice how the second image appears to be sharper than the first? (Note: With the 100K file size limit for Registry Set images, the pictures can been even larger and sharper.)
Now I have the 1852 image I needed as well!
Huh?
The two 1852 pics look the same to me. I don't get it unless my eyes are playing tricks on me.
Help!
The differences are rather subtle, but to my eyes the second picture is in sharper focus than the first, with the only difference being the level of resolution of the original scan.
Perhaps the differences would be clearer with larger images and a larger difference in resolution. Following are images of the Rudolf 1865 dollar, scanned at 100dpi, 300dpi, 600dpi, and 1200dpi, and then letting the Adobe software (rather than the scanner) reduce the images to 72dpi for internet posting. I think you can see how each successive image is somewhat sharper than the one before, and at the 1200dpi level, you can still enlarge the image and have it remain quite sharp.
Scanned at 100dpi:
Scanned at 300dpi:
Scanned at 600dpi:
Scanned at 1200dpi:
Does this help?
Hope these help!
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However, why is the 1200 dpi example much larger than the other three? Also it appears to me that the 1200 dpi lost some of the sharpness that the 600 dpi picked up over the 300 and 100 dpi?
Now where DID you learn all of this stuff?
He's a very smart person!
How does one get a hater to stop hating?
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