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Old Dec 31, 2002, 2:07 PM   #1
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Default Pixels / Resolutions / Images

Hey everyone. I'm new to this forum and in fact new to digital photography.

I work in a marketing department designing printed sales and support literature. So my background is definitely in the "printed" world. I primarly use CorelDraw, Corel PhotoPaint and Fireworks.

This whole "digital" concept is confusing me.

I'm trying to make the manuipulation / printing of my photos as fast as possible. (I'm figuring if I spend hours on the computer messing with my pictures, I could have taken a roll of film in for processing much easier.

My background tells me all printed pictures need to at 300 dpi resolution. So do I need to resample every digital picture?
I was told NOT to resample as I would lose quality. I was told just to resize my photo to fit my media, 5x7, 8x10, etc. They also told me as I resized, my resolution would increase.

Unfortunately, when I reduce, indeed my photo gets smaller but I never actually see the resolution increase. It seems to stay at 72 no matter what I do, unless I resample.

Please help this old girl understand this whole process. Thanks for any hints you can give me.
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Old Dec 31, 2002, 2:34 PM   #2
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Have you tried shooting digipics, quick look to chuck out really bad ones (get those better next time!), DON'T edit, just upload to an online service or take your card into Walmart?

Remember that they may need to crop for a 6X4 print and their choice (eg top down/bottom up) might not be yours (centre, balanced), so that is probably the only thing you might need to do beforehand. You could ask or try a couple of test prints to see which way they go. Their machines will take care of the sizing.

This might not sound much fun, but that comes later on with the 'specials' The commercial printers are 300dpi but on real photographic paper.

I have an oldish version of CorelPhotoPaint, but I don't find it as friendly as Ulead PhotoImpact or Photoshop. Corel is good on the effects/warps etc but it's a bit memory hungry on loading, whereas the other editors seem more featured to the bis of digipic work.

When you shoot your original image the real pixels are what you make. Forget the words for a mo. Ideally, for a given size of print say 6 X 4, those pixels will be placed on the paper and you will have the equivalent cam number horizontally and vertically. For a bigger print those pixels will be more spaced out (lower resolution) for a bigger image. Go smaller, the pixels get closer and res. gets higher.

Unfortunately, what we view or print with does not output exactly match/map the same proportions. A monitor is approx 72 dpi. So every 72 of your original cam pixels is 1" on you monitor i.e VERY BIG. A printer might be 300dpi, so every 300 pixels would print an inch.

The conundrum is you want a specific output size so the software has to change the original number of pixels by evenly adding or subtracting, so your monitor/printer when dividing by 72/300 gives the image size you want.

This jiggery pokery is OK to do once for your output, but you must always keep a copy of the original cam file unaltered. So here's an example: Say you want to put a photo on your screen 6 X 4. You need to scale 72dpi, that's about 482 x288. from your original image. Your software will throw pixels away until it gets these numbers. You can never get more pixels/resolution than the output device is capable of. I've had to explain this, because I know CorelPhotoPaint print size and res. options can be confusing and a little bit of 'rithmetic is needed.

However, life is much simpler. Qimage Pro (check Steves Software section) allows you to enter your print size and the software works out the numbers from your input file. Similarly, Walmart printers do the same thing but in both cases cropping has to be done because your image frame is different to the paper frame size. Qimage Pro is great because you just move the image around in a print frame. Unfortunately, my version of CorelPhotoPaint needs the 'rithmetic - so I sympathise, sorry this is a long post.
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Old Dec 31, 2002, 2:40 PM   #3
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Printing is one of the more difficult concepts...cameras use the computer dpi (72dpi) setting,so you do have to do some resizing...for instance at 1600x1200 is 22.2x16.6 inches at 72dpi gets converted to 10.6X8 inches at 150dpi and 5.3x4 inches at 300dpi.

In Corel Photopaint (9), when you got an image open go to Image, Resameple, make sure Inches is selected from the dropdown, "Maintain Original Size" is checked (may also want Maintain Aspect Ratio and Anti-Alias also checked), and then change the number of inches...or you can use the numbers above if you have a 1600x1200 image.

This may be a nuissance, but some other things may also need some other work, like sharpening, Auto Equalize, and cropping.

You have to remember that with digital cameras you are missing the role of the darkroom/processing lab, so you have to play that role.
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Old Dec 31, 2002, 10:16 PM   #4
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Quote:
In Corel Photopaint (9), when you got an image open go to Image, Resameple, make sure Inches is selected from the dropdown, "Maintain Original Size" is checked
I'm not familiar with Corel, but aren't "Resampling" and "Maintain original size" mutually exclusive? I mean, doesn't resampling change the original size?

Dan
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Old Dec 31, 2002, 10:28 PM   #5
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That's the way it's done in Corel...by doing it that way you aren't resampling, just resizing. As long as "Maintain Original Size" is checked, it doesn't resample. Sometimes I forget and that changes the image, but with this method you are changing the dimensions without altering the image.
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Old Jan 1, 2003, 5:30 AM   #6
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One way to make sure it's not altering the original image is to go Explorer, right click filename, properties, 'write protect' before starting Corel! - My version then warns that 'Save Only' is disabled, but you can save as a new filename. I lock all files in my cam original folders this way.
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