Nikon D3200

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zzoldtown
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Nikon D3200

Post by zzoldtown »

I know it's not cheap ~$700 w/ lens
however it's a DSLR from Nikon w/24MP

Has anyone used it , or can weigh in to how much of an impact it'd have on scanning in general and OCR in particular.
dpc
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Re: Nikon D3200

Post by dpc »

Can't comment on that particular camera but I use a pair of Canon DSLRs in one of my scanners and they cost about the same amount. Being able to use better lenses is a big advantage over the smaller, less expensive point-n-shoot cameras. You don't get blurred edges on the text as you move farther away from the center of the page. I'd go with mirrorless if I were you, as fewer moving parts means less things to wear out over time (scanner cameras will be shooting a LOT of photos).

Also, look for the ability to view the camera's preview image on a larger monitor or laptop display (running camera mfgr software) so that you can easily determine what the shot will look like without having to move your head to look at the camera's small display when scanning. Look at what software is available from the manufacturer for remote capturing photos and doing live preview. I chose to go with the Canon cameras because they have a free SDK that allows you to develop an application that can control every aspect of their DSLR cameras with an attached laptop over USB. Maybe Nikon has something similar and someone has written something that you could use if you don't want to go to the trouble to develop the software yourself.

Regarding OCR, a lot of this depends on your OCR software. Before you blow money on a fancy camera, capture digital screenshots of a page of text from an e-book that you're viewing on your PC or phone. The resulting image will represent the best image you could ever hope to get from photographing the page of a book. The lighting will be perfect. Every bit of text on the page will be in focus. Now run that through your OCR software and see how many errors you get. If you get no errors, then load the screenshot into Photoshop or some other image editing software and dirty it up. Darken the entire image, or use a gradient to darken at different levels across the image to represent uneven lighting and then run that through your OCR. You can even add noise to the image and see how that affects your OCR, or play around with resolution changes to mimic a smaller camera sensor (fewer MP). This will give you some idea of how good the images must be in order to get accurate results from your OCR'ed images. It could be that using the better camera doesn't buy you much. This sort of experimenting is a cheap way to find out.
cday
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Re: Nikon D3200

Post by cday »

dpc wrote: 16 Jul 2022, 18:25Regarding OCR, a lot of this depends on your OCR software. Before you blow money on a fancy camera, capture digital screenshots of a page of text from an e-book that you're viewing on your PC or phone. The resulting image will represent the best image you could ever hope to get from photographing the page of a book. The lighting will be perfect. Every bit of text on the page will be in focus. Now run that through your OCR software and see how many errors you get.
@dpc: But wouldn't the number of pixels be much lower than in a modern camera image?

A Full HD screen has 1,920 x 1,080 pixels, which is around 2MP, yes you might have a higher resolution screen, but still many fewer pixels than a modern camera...
dpc
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Re: Nikon D3200

Post by dpc »

Yes, the DPI will be dependent upon your screen resolution, but I'd wager that the OCR accuracy will approach 100% even with the lower DPI because of the "cleanliness" of the image. If it doesn't, you could incrementally increase the size of the text prior to the screen capture and see how large you need to go before the OCR produces a correct result. That would give you some idea of the camera resolution you may need.
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