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Photo Restoration Repairing damaged photos

File size issues

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  #1  
Old 04-15-2006, 10:49 PM
imann08 imann08 is offline
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File size issues

I have been scanning photos in a basic all-in-one flatbed and when I scanned a photo at 1200ppi I got an initial file of like 130mb. When I converted that file to photoshop and started working on it to restore and colorize it, it turned into a 600+mb file very quickly. That's insane and something I have never dealt with before.

The bottom line is that 1200ppi is low when it comes to scanning resolutions nowadays and if I were to get a scanner that does 2400 or even 4800 I'd end up with a file many GBs big. A few photos and I'd have to get a new hard drive. Anyways, is this the norm and something I should expect? Should I be scanning at high resolution and the bringing it down to, say, 300ppi once I get it into PS? I'm a bit confused.
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Old 04-15-2006, 11:38 PM
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mistermonday mistermonday is offline
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If you are scanner in an image with 12 to 16 bit accuracy, then your file at 16 bit will be 2 X the size of an 8 bit image. 16 bit is much better to have prior to doing all of your edits but when you are finished editing, you can convert to 8 bit beacause your printer can't the full 16 bits. (BTW, saving an archive copy of the 16 bit image on a DVD is a good idea.

Next if you are saving layers (.psd or .tiff), then each layer could be as large as your background. This will grow the file pretty quickly. Try merging some layers where you can. You can also reduce the file size by saving as a TIFF with lossless compression. And of course a jpg will offer you a much reduced file size at the expense of some quality which will not be noticed if you use a high setting like 12.

As for the resolution, if you plan to print these images, then your file should be 300 DPI for the maximum size. For example if you plan to print a max 8 x 12 inches then your image size should be 2400 pixels x 3600 pixels.
If you are scanning a photo which is 2 x 3 inches and you plan to print at 8 x 10 then you will need to scan at 1200 PPI in order to get 2400 x 3600 pixels.

Regards, Murray
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Old 04-16-2006, 12:18 AM
imann08 imann08 is offline
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So let me get this straight. The only reason to scan at higher resolutions is if you want to increase the size of your printed image? What is the minimum resolution that one should scan at? For instance, if it is already at the size that I want it at should I just scan at 300ppi? Also, my current scanner has only has 8bit. That is why I asked the question about scanners and printers. I am totally inept in this area. My main concern about file size is not so much about what I am storing the file at but what I am editing it at. For instance, if I edit a file that I scanned at say 2400ppi 16bit, then I'll be working with a file on PS that is multiple GBs big. That doesn't seem right and it would slow down my PC to a crawl. Should I resize my file to where I want it at 300ppi immediately before editing it while keeping it at 16bit?

I don't like to merge files if at all possible as I find myself going back to edit things later on in the editing process. I also store stuff in the PSD format and not tiff. At least I have up until now cause it hasn't mattered.

Please clarify this if you can. Thanks a bunch.

Isaac
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Old 04-16-2006, 12:52 AM
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Craig Walters Craig Walters is offline
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imann,

you dont gain a lot after about 300 dpi on most photos, at least not for 'normal' photos. there are exceptions, particularly if the image is in bad shape and picking up detail is super-crititcal.

and the other consideration on this is that, how are you going to end up displaying it. print doesnt need more than about 200 dpi. web viewing is even less, though some are fanatics on this one and demand much higher. the last commercial printer i sent anything to said 'no larger than 200 dpi'.

but there's always the quirks. and your workspace isnt necessarily what you are going to display in. i often double or triple the size of an image when working, just for some detail thing or to keep from adding 'jaggies', but then shrink it back down for display purposes. and you'll also find a plethora of varying opinions on this stuff. some swear by 2400 dpi. i find it mostly worthless. in fact, almost everything i scan at home is at 300 dpi and i'm quite happy with it.

now negatives, that's a different story. i dont scan at anything under 1800 dpi and use a dedicated negative/slide scanner.

also bear in mind that some manufacturers tend to lie a bit. their '2400 dpi' is really only 300 or 600, but they simply do a resizing to get the 2400, much the same way that photoshop can resize. camera manufacturers do this also and call it 'digital zoom' as opposed to 'optical zoom', which is the real thing.

so, what it really boils down to in the end is, what are YOU happy with? what can YOUR eye discern?

craig
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Old 04-16-2006, 02:02 AM
imann08 imann08 is offline
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Pretty much every thing I do is going to be printed although I will still do the occasional web design but that's really not what I'm asking about. It mostly just for the case of photo scanning. For the most part I always make things for print at 300ppi. I don't think I have ever done it differently although I know less is excepted.

Essentially the larger resolution you scan at has two benefits as I get it. The first is it enables you to enlarge an image for print. The second, is that it enables you to zoom in very close to your image without the jaggies. My main problem that I would have in scanning at ultra high resolutions which I will call anything 1200 or greater, is that I will quickly have a file of more than one gig and it wouldn't surprise me to have one of many gigs if it was 2400 at 16bit. So generally, my question on this issue was answered. I usually like the best I can get but have to take file size into account. I am at 2gb of RAM but that's maxed out my PC and I can't go any higher. I am also running a 3.2P4 with HT but it still bogs when I start running files that large.
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Old 04-16-2006, 04:40 AM
happysnapper happysnapper is offline
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First decide how big you want to make your print so lets say 12x8

To find out how many pixels you need to print this you multiply both sides by 300 (dpi) = 3600pixels x 2400pixels

If you are scanning a 6x4 to start with then divide each side by the inches
3600/6=600 and 2400/4=600

ie to scan a 6x4 to print at 12x8 you need to scan it at 600dpi.

If you want to print something out to keep for reference, try this

http://www.1stopphoto.co.uk/factsheets/dpi.pdf


HTH
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Old 04-16-2006, 10:54 AM
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mistermonday mistermonday is offline
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Isaac, its too easy to get hung up in the resolution numbers. Instead, try to think of the actual number of pixels you have that make up an image. As an example, visualize an 8 x 10 sheet of paper cut into 80 squares of 1 x 1 inches each. Now each square can only be a single color. If you were to try and build a photo of yourself with just those 80 single colored squares, it would be pretty jaggy. As you make those squares smaller and smaller (and more of them), you reduce the jaggies until at some point you get what appear to be smooth transitions. For photo quality printing. it is generally accepted that you should have 300 ppi (newsprint, magazines, posters are lower). Always consider your max intended output. So if you intend to scan a 35mm negative and you want to print it at 8 x 12, you will need 2400 x 3600 pixels of info. The only way you can get that amount of optical image data is to scan the negative, which is 1 x 1.5 inches, at 2400 ppi. In fact you will find that all dedicated film scanners have a minimum optical resolution of 2400 ppi.

BTW, 2400 x 3600 is only about 8 million pixels which is about a 24MB size file for a single layer. That shoud be quite manageable when you get a reasonable number of layers. I am not sure why your file sizes are so large other than your scanning at too high a resolution for the size of print you have. If the image you are scanning is already at the print output size, then all you need is 300 ppi unless you need more data because you will be cropping the image and enlarging it.

Another thing to remember when working in PS is that it only uses a portion of system RAM to work in. It tends to use the scratch disk a lot for temporary manipulation and storage. Therefore having a fast processor is only part of the speed solution. The other factor is to have fast hard drives. 7200 RPM SATA drive which is physically separate from the drive on which your Windows OS resides, will in many cases give you more speed than a faster processor because the processor is not the bottleneck.

Regards, Murray
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Old 04-17-2006, 12:49 AM
imann08 imann08 is offline
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Thanks Murray. I get it now. I was just concerned with the file sizes I was ending up with and I now understand that the resolution I was scanning at was totally not needed. I already had it at almost the print size anyways. It was 4.6x6.7 and I wanted a 5x7. I had scanned it at 1200 and was doing all my editing while it was still at that size. I understand now that if I want to increase the output size then take care of that right off the bat to get the file size to a respectable amount instead of staying in 1200 or whatever I need to increase the size. My computer is plenty fast but I do lack in some areas such as bus and hard drive. I do have a 3.2P4HT though with 2GB of RAM. That is plenty for pretty much everything I need.

Isaac
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