How high is high res?

So far I've made pics around 2-4 MB.

I just saw on a stock photo site that they sell pics at more than

60MB!

What is needed for printing a book cover?

Should I start working at a higher resolution???

 

Thanks,

 

NewB

2-4 MB doesn't sound like much. A number in megabytes is not a measure of resolution, just disk space. Which varies enormously between files of the same megapixels (MP) depending on compression, encoding, bit depth... You need to know the MP not the MB!

That's 60M with absolutely no compression. For example, a 6MP image is 2000x3000x48 (16 bits per channel) = 34M. But as a compressed NEF or as a LZW compressed TIFF it will be much smaller despite these being entirely lossless formats. As a high quality JPEG, with no perceptible loss of quality, it will be even smaller.

 

I don't know why the "professional" stock agencies think the size of the file is anything to do with the quality of the image in this day and age. But what the hell, it's their disk space, just uprez your image if necessary and save it in the most inefficient format you can to make the size requirement, they're happy.

60MB is the 8-bit, uncompressed file size. This comes out to something like 6000 x 4000 pixels or thereabouts, which is a bit more than what's required for a double-page magazine spread. When a stock photo agency delivers these files electronically (email, FTP, etc), they usually send it as a jpeg, which can be as small as a few MB after its been compressed.<p>

 

When you say 2 to 4 MB, are you stating the file size after jpeg compression? Or is this the file size when viewing it in Photoshop?<p>

 

Book covers vary in size, so you'll need the book dimensions before determining file size requirements. 300dpi resolutions are a standard for printing, so multiply each dimension by 300 to determine the required pixel dimensions. For a book measuring 9x12 inches, you would need pixels dimensions measuring 2700 pixels by 3600 pixels. If you multiply these pixel dimensions together, you'll have the total number of pixels: 2700*3600=9720000, or approximately 9.7 megapixels. If you multiply the number of megapixels by 3, you'll get the approximate 8-bit, uncompressed file size. For a book cover measuring 9x12 inches, you'll need a file size of approx 29 MB. If you compress this as a jpeg, you'll end up with a much smaller file size. How small depends on the jpeg compression and the amount of detail in any particular photo.<p>

 

Hope that helps.

Monique-- Most high-quality magazine and book reproduction requires 300 DPI at the final size that the image will be used. For example, if the image will be used 2 x 3 inches, then the image should be at least 600 x 900.

 

JPEG compression can make this smaller than a straight TIFF file, and thus it is possible that the file size can be smaller than what would result when you multiply the two vectors (600 x 900 = 560,000, unless I counted the zeros wrong). However, note that in the compression you will lose highlight and edge detail, and that does not account for the bit multiple for the colors.

 

Many printers will specify a file sized based on a TIFF file that will give them minimum resolution for their final output size.

 

Happy shooting. -BC-

60 MB dates from film scanning. A 4000 dpi, 8 bit scan of 35mm film yeilds a 60 MB file. While it doesn't make much sense for direct digital capture, it's a number that's still out there.