When a member of my family asked me earlier this week what my ‘new year resolution’ was, I was tempted to answer “300 dpi”. I would have laughed but I’m afraid that the rest of the family would have just given me that old-fashioned look that says “Neil is laughing at his stupid jokes again”. For the record I want to get fitter, lose some weight, shoot better pictures and love everyone.
To photographers, designers and anyone else who handles photographs resolution is an important concept. Get a few photographers together and someone will complain about a client whose comprehension of the concept of resolution is so poor that they have rejected huge files just because they hadn’t been saved at 300 dpi. What is 300 dpi anyway? Does it have any relevance in todays’ digital world?
Put simply, DPI is an output term. It describes the number of dots per inch that the printing system will place onto the paper and, generally speaking, the more dots you have the better the quality. Of course if you have cheap paper that soaks up ink too many dots just produces a mulchy mess. Newspaper quality is a case in point: try to stick more than the right amount of ink down and the paper will get soggy and rip whilst going through the presses. Your inkjet printer at home might be capable of 2,880 dots per inch but that doesn’t mean that you have to save your pictures at that size. So much software these days has the ability to re-size and re-interpret images to make them work.
Don’t get me wrong, it is always best to send pictures to commercial printers or reproduction houses at the right size at the correct resolution and properly sharpened but some of the nonsense talked by people who don’t understand is very frustrating.
Photographs are actually measured in pixels per inch or pixels per centimetre but even that misses the point. What actually matters is the number of pixels that make up the image. You can have a picture that measures 3,000 pixels along one side and 2,000 pixels along the other (6 million pixels in all) and that is really the important fact. At 72 pixels per inch (the normal internet resolution) that would appear as a huge picture. If the same 3k x 2k pixel image was saved at 150 pixels per inch (about normal for newsprint) it would still be 50cm wide whereas at 300 ppi it would be 25cm wide. Actually switching between resolutions is easy and it makes no difference to the image quality (unless you repeatedly re-save in a lossy format such as Jpeg). All that really matters is the number of pixels.
Even going back to the days of scanning negatives on the venerable Kodak RFS machines into Photoshop version 2.5 where an original 35mm image measured 24mm x 36mm (that’s 864 sq mm) meant that every picture was still 24mm x 36mm but had a resolution measuring up 2500 ppi it was a few clicks of the mouse to change the picture to the required resolution at the required size with no damage done – with the possible exception that the low power of the computers meant that it took more than a few seconds.
Exactly who trained these people who don’t get this concept is beyond me. It is as simple as it is logical. My new year resolution is, therefore NOT 300dpi. I’m going for 254 ppi or 100 ppcm along with a bookmarked link to this blog piece so that I can refer people to it as, and when, required.
Neil Turner Photographer 