 Benjamin Baron |
scanning pictures I am trying to save old photos and I want to scan them ,what would be the best resolution to use in the scanner? Thanks
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robert G. Fately |
Ben, this involves the trade-off between how big you want the files to be and what you plan to do with the images at a later time. Scanning at a high resolution would give you more flexibility in the future - say if you wanted to print a 16x20 print of grandma, or, more likely, if you wanted to make a 5x7 print of just a small portion of the total picture you scanned (where you'd have to crop out a small part and still will need the details captured to enlarge that to 5x7). Of course, to use two extremes, if you scan a 4x6 at 300dpi you're looking at files that are about 2MB (uncompressed) versus scanning at 1200 dpi which would jump to a file size of about 32MB each. The former would be fine for screen displays or prints up to perhaps 8x10, the latter could enable you to make much larger prints. So, a useful compromise might be to use a relatively low resolution for your generic shots (maybe 300 or even 600dpi) that you don't figure will even be printed in any large size, while using a higher resolution for any images that you think you might, some day, want to make into larger (or cropped) enlargements. By the way, whatever you decide, be aware that you should only use the optical resolution of your scanner - many models claim higher "virtual" or "digital" resolutions, which are as useless as digital zoom is on point & shoot digicams. So if your scanner does 1200 dpi optical, 4800 interpolated - just limit yourself to the 1200 dpi setting. Finally, if you're going to all the trouble to scan these images for the purpose of saving them, consider your backup stratey. Perhaps burning multiple CDs or DVDs (the high quality gold type, not the cheap stuff at the drug store) and storing them in multiple locations.
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Michael H. Cothran |
Ben, As a rule of thumb, it is always best to scan to the highest resolution afforded by your scanner. You can always size down afterwards, if necessary. Why put yourself in the position where you may have to scan the same film or print a second or third time because you need/want a bigger file later on? Scan once at the best resolution you can, and be done with it. Michael H. Cothran
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John P. Sandstedt |
It's all in the numbers and, as said before, you have to decide what size print your want. In his book B&W Digital Printing, George Schaub gives a nifty table showing how many megapixels and/or megabytes you need for prints of various sizes. Needless to say, I haven't got my copy of the book with me as I write this response to your question. So, I'll tell you what I actually do - I scan a 4X6 at 600 dpi and tell the computer/scanner to produce a 4X6 picture in the file. If I can, I do some cropping before scanning but I still try for a 4X6 at 600 dpi. This results, typically, in 16-21 MB file, svaing to PSD or TIF format. I do this to maintain data. All editing will impact [destroy] data and so, for example, additonal cropping will shrink the file a lot or a little depending on how much is cropped. but remember the data loss is a function of the total area removed and therefore can be a large percentage of the starting number. That's one reason why I want lots of bytes. I do all editing, including as a last step - the Unsharp Mask with this file, often making a separate copy for each edit. Now I'm ready to print. If I want a nominal 8X10 I adjust the picture dimensions [I normally set 10.5 in. as the longer dimension when I print on 8.5X11 paper] and reduce the resolution to 240-320 ppi [normally 300.] No more in needed - any more ppi higher resolution can't be utilized by most inkjet printers. The resulting file maintains the ~20 MB size [TIF.] If I want to print a 4x6, I just change the resolution to 300 ppi. The file size drops to ~6 MB [TIF.] I just got a Canon i9900 which makes 13X19 prints. According to George's table, one needs At least 50 MB for a 12X18 image. I've scanned 35 mm negatives to produce, directly, a 300 ppi file with 12X18 dimensions. Typically I get a 45-60 MB file. I've also scaned with resolution to 1200 ppi from negatives, slides and prints. Some of the files were pretty huge [up to 155 MB,] so that's why I most often scan for these large prints at 300 ppi.
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Benjamin Baron |
Thanks for the tips , I will try them out and see how my prints come out. Ben.
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