When getting prints developed from your digital camera, does the size of the file indicate quality?

Question

high quality big file, low quality small file. (3 MB vs 500 kb)

Or is the Pixel rating ie (3000x2000 pixels PSI) or (300x600 pixels)

or like another example would be resizing a 3 MB picture to 1 MB...would the prints come out the same? or is it really that noticeable? thanks. again

Answer 1

The file size and the pixel rating can both be used as indicators. A bigger file / more pixels is always better.

To be more precise, the file size reflects two things and the amount of pixels is one of them. The more pixels, the bigger the file. The other things that file size indicates, is the amount of compression. Just like the MP3 format uses compression with audio files, the JPG format uses compression with image files. The less compression, the better the quality, and the bigger the file size.

Just about all cameras have settings to change the image size (amount of pixels) and the quality (how much compression to use) independently. The combination of these two settings determines the file size.

In my personal experience, a 500KB file will produce great 5x7 inch prints and a 3MB will even produce fantastic full page prints. A 3000x2000 pixel image will also be good for full page prints. A 300x600 pixel image however, won't look good at anything larger than the size of a stamp.

If you're interested, you can do the math for maximum print size. For great print quality, you'll need 300 pixels per inch.

With a 3000x2000 pixel image, this translates to a maximum recommended print size of
3000 pixels / 300 pixels per inch = 10 inches wide
2000 pixels / 300 pixels per inch = 6.7 inches high

With a 600x300 pixel file, you'd get a maximum recommended print size of just
600 pixels / 300 pixels per inch = 2 inches wide
200 pixels / 300 pixels per inch = 0.7 inches high

So the pixel count is a quantity issue; it limits the print size. On the other hand, the amount of compression is a quality issue. Too much compression will ruin a picture at ANY print size. Just like using a crap lens, or bad technique & blurring will ruin a picture at any print size. How much compression is TOO much? That's a peronal call. I personally use as little as possible.

I keep my camera at maximum resolution and maximum quality all the time. This way, I can use every picture for a full page print. (You never know when you might want to submit a lucky grab to National Geographic :-) This gives me JPG files in the 3 to 6 MB range. If I want to use those pictures for my website, or if I want to email them, or just save the picture as a small file (so I don't fill up entire hard drives with snapshots) I make copies at 800 x 600 pixels AND I compress the quality. This reduces the file size from 5 MB to around 70KB... no longer suitable for prints, but sufficient for viewing pictures on a computer screen.

As for reducing the file size from 3 MB to 1 MB, that sounds like a decent compromise... the new files will still be good enough for prints, they won't fill up your hard drive so fast, and you can include 2 or 3 in an email attachment without blowing up someone's in-box. But the prints will not look as good as the originals, particularly at larger sizes.

Answer 2

There is some misinformation here, because people confuse the pixels per inch of a sensor with the dots per inch of a printer. It's a common misconception.

Let's answer your basic question first: The answer is that the more information you have, the better output you're going to have. So in this case the 3 megabyte file and the file with more pixels (3000 x 2000) will give you the best results.

Now, when printing at home, what happens is that your file will be converted by the printer driver and sent to the printer to make a print. Depending upon what program you're using to print at home, it can affect the quality of the print, resulting in jagged lines or lower quality, because printers have a "native" dots per inch resolution. For Canon printers that's 300 dpi, but for Epson it's 360 dpi. Where the math comes in is that tagging the file to it evenly divides into either 300 or 360 depending upon your brand of printer. Thus for a Canon, a print tagged at 150 dpi will print better than tagging it at 200 dpi, just because the math will work out better for the printer driver.

Don't confuse pixels per inch and dots per inch, because all files are interpolated by a printer driver. Even pros get this confused. A really good printer driver can take even a fairly moderate pixel count image and blow it up very nicely. There are companies which specialize in printer drivers for specific high-end printers. It's this interpolation which makes the difference. Otherwise, you'll fall into the trap of believing that you can only make a 10" x 6" print as the maximum quality size from your 6 megapixel (3000x2000 pixels) camera. It's just not true.

For home printing, my suggestion is to get Qimage, http://www.ddisoftware.com/qimage which automatically takes care for converting your image info to the right dpi for your printer driver and allows for simple, easy printing at the highest quality.

Answer 3

yes, the size of the picture matters when one talks about quality of the picture. if a 50 kb were to be enlarged, the pictures will end up to be pixelized, whereas, if a 7mb picture were to be enlarged (or turned into a tarp sign, as big as 2' X 4', the picture quality will not be affected.