1.2, 2.1, 3.4. Those numbers sound familiar? They should. They're the megapixel resolution plateaus for digital cameras over the past three years. Graph them and you can easily guess where resolution is headed for the future.
There are photographers just drooling for higher resolution cameras in the belief that they'll make better pictures with them.
This column is intended to put a different slant on resolution and pleasing images, plus solving a problem that plagues the recipients of digital photos as email attachments.
It's all about image size.
The raw image that downloads from your memory card to your computer is usually a monster. Somewhere between 16 and 29 inches wide at 72 pixels-per-inch (ppi). And uncompressed from JPEG, it's also a file of whoppin' size.
From my 3.4mp camera, a raw file is 9 megabytes in a format of 28.4 inches wide at 72ppi.
Many folks consider that the finished picture and blithely attach it to their emails, causing great vexation among recipients who have to use their browser scroll bars just to get from one side of the image to the other.
Others tear out their remaining hair by trying to print one of these brutes on an inkjet.
It's all about image size and the answer lies within Photoshop (Menu: Image>Image Size). When you open Image Size, you're confronted with a dialog box that has two sections. The top one shows you the current file size and dimensions in pixels. Multiply those pixel dimensions and you'll arrive at the resolution of your camera.
The lower section provides current dimensions and resolution in three controllable boxes. I prefer to uses inches for my dimensional measurements but you can use any of a number of measurements including percentage.
Photoshop's default has these three windows linked together with the "resample image" checkbox turned off.
Changing the image size to something workable is simply a matter of entering either one dimension or a new resolution. For my travel stories, I prefer to convert my images to a standard of 8 inches on the long dimension. So, by selecting the width dimension and replacing 28.4 inches with 8 inches, I achieve a 6x8 image with a resolution of 256 pixels per inch. The file size remains 9 megabytes.
This is a size and resolution that will make an excellent bordered 8x10 print at 1440dpi (or higher) on an inkjet printer.
But what of the web or multimedia designer or the photographer who just wants to send email attachment images? Certainly a 9mb file is too big to be used.
The image size procedure is exactly the same except this time, the "resample image" feature is checked on. Now only the image dimensions are changed with the 8 inch width resulting in an image 576 pixels wide, just right for attaching as an email.
The file size reduces to 729K and when saved as a high quality JPEG (8) compresses to 108K.
Web designers will want to be even more specific in their sizing and use Photoshop's "Save For Web" feature to achieve the greatest resolution at lowest file size.
There's no doubt that higher resolution cameras will capture more detail and provide greater sensitivity range. However, I've found it very difficult to tell the difference in 1440dpi (or now 2880dpi) inkjet prints made from image sized 2.1mp images as opposed to 3.4mp images.
This will no doubt cause scoffing anguish from the megapixel zealots. However, if you're in the market for a digital camera and accept this premise, you'll be interested in next week's column on holiday shopping.
Jim
Patterson was a respected, trusted resource for anything
to do with digital imaging and a regular digital photo
columnist for Mac Design Magazine and contributor to
Photoshop User magazine. He passed away the summer of
2004. Jim was frequently-published as a freelance travel
photojournalist, and authored the novel, "The Thirteen." There
was much more to Jim than just a writer, and he was much
more to us than just a friend.
