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Technical question about Photo Frenzy
September 28, 2009 - 9:27am
I hope there are some image science or photography folks in the watch that can help me understand the photo frenzy requirements: "JPEG images, and should be approximately 4"x6", at 300 dpi. The file size of the image should be no larger than 2MB."
I've always understood dpi as a PRINTING specification and not something that is directly related to the camera or even to the image itself. I would think that what I would need to supply is an 1200x1800 pixel image that would print at 4"x6" on a 300dpi printer. This means that all I would need to do is set my camera to 2 megapixels and save the image at a full size jpg file.
Am I missing something here?
September 28, 2009 - 10:44am
#2
Thanks, dev, that helps. I googled and saw a reference to setting printer resolution to 300 dpi in Photoshop so that the jpg file specifies the printer resolution, and I was wondering if they expected us to do that. I don't have (and can't afford!) Photoshop, but I do have GIMP and perhaps it includes that functionality. Is this something I should try to do?
September 28, 2009 - 11:38am
#3
You could either try and use GIMP to put that in the JPG header, I'm not sure if you can or not in the program. Or you could just make sure your image is 1200x1800. I'm assuming that the 300 dpi is what the newspaper is printed at, so they probably have a program that automatically sets the dpi. Which means if your image is 1200x1800 and they have it auto-set to 300 dpi, it'll come out as 4"x6".
September 28, 2009 - 6:39pm
#4
You are correct - the 300dpi is because the winners might be printed in the newspaper.
September 28, 2009 - 8:59pm
#5
If you are sending us a file that is roughly 2MB when you email it, then you will be fine. Don't get hung up on the exact dimensions. Those are just a ballpark so the winning photos can be printed in the paper. We were trying to find a happy medium between tiny images and ones that are so huge our inboxes were jammed up.
-- Christina Dicken, Photo Editor at the D&C
I have my BS in imaging science and i'm currently a phd candidate in the same program.
Yeah you are correct, dpi is a printing term or rather a physical term so it applies to other display devices as well. Resolution just tells you the number of samples, not how big they are. You are also correct in saying to print a 4"x6" at 300 dpi you need at a minimum a 1200x1800 image make a 'good' image. You can force anything to print at 4"x6" at 300 dpi, it just depends on how much interpolating will go on before the image is printed. A 1200x1800 image will need no interpolation. A smaller image will need an upscaling interpolation, resulting in a blocky looking print. A larger image will also need a downscaling interpolation, resulting in a loss of information and possibly a small blur from the original.
So moral of the story is: If they're going to print this image (which it sounds like they might) all your images should be at a minimum 1200x1800 pixels to look good.
Also it seems that because they are supplying those instructions, if you take a larger or smaller image I think they want the image to be resized so it is 4"x6" at 300 dpi (1200x1800 pixels)