Keith
02-25-200725th February 2007, 06:33 PM
I thought this would be a great article for all of you to read especially those who luv to print. I was of the same belief, and now my opinion has changed!
Testing your printer's resolution
There has been a lot of talk lately on the web questioning the rationale for sending more than about 240 - 300 PPI to a printer. Some argue that sending more than about 240 PPI does not improve prints and also question whether the unaided eye can see more than 240 PPI even if it improves printed results. Others cite studies based on human visual acuity and try to equate results of tests related to the human eye directly to print DPI, often ignoring issues such as Nyquist frequency, aliasing, and other important aspects that affect print quality and resolution. Many of the "studies" that come to such conclusions are based on poorly chosen mathematically derived test charts or photos that don't contain enough detail or original data to properly test printer resolution limits. It's difficult to test printer resolution when, for example, you print a 10x8 print from a 6 MP camera where you only have about 300 PPI of data to start with since interpolating to 600 or 720 PPI will result in only subtle differences when compared to simply printing the original 240-300 PPI image. Print a 4x6 or even a 5x7 where you are starting with more than 300 PPI of detail in the original image, and differences in print quality go from subtle to obvious. As cameras break the 8 MP barrier and beyond, the size at which detail above 240-300 PPI can be realized and easily detected in print will increase, allowing detail far beyond 300 PPI to be resolved even at 8x10 and larger print sizes.
Take the Qimage challenge, I just did this yesterday and I was amazed at the results at 600dpi which is Canons native resolution.
Read here and the test sheet is available for Epson 720 dpi and Canon 600 dpi. If you dont own Qimage, there is a 30 day free trial. Just got my new Canon printer and quite impressed. Hence all the reading on printing lately, best half hour you will spend :)
http://www.ddisoftware.com/qimage/quality/
Testing your printer's resolution
There has been a lot of talk lately on the web questioning the rationale for sending more than about 240 - 300 PPI to a printer. Some argue that sending more than about 240 PPI does not improve prints and also question whether the unaided eye can see more than 240 PPI even if it improves printed results. Others cite studies based on human visual acuity and try to equate results of tests related to the human eye directly to print DPI, often ignoring issues such as Nyquist frequency, aliasing, and other important aspects that affect print quality and resolution. Many of the "studies" that come to such conclusions are based on poorly chosen mathematically derived test charts or photos that don't contain enough detail or original data to properly test printer resolution limits. It's difficult to test printer resolution when, for example, you print a 10x8 print from a 6 MP camera where you only have about 300 PPI of data to start with since interpolating to 600 or 720 PPI will result in only subtle differences when compared to simply printing the original 240-300 PPI image. Print a 4x6 or even a 5x7 where you are starting with more than 300 PPI of detail in the original image, and differences in print quality go from subtle to obvious. As cameras break the 8 MP barrier and beyond, the size at which detail above 240-300 PPI can be realized and easily detected in print will increase, allowing detail far beyond 300 PPI to be resolved even at 8x10 and larger print sizes.
Take the Qimage challenge, I just did this yesterday and I was amazed at the results at 600dpi which is Canons native resolution.
Read here and the test sheet is available for Epson 720 dpi and Canon 600 dpi. If you dont own Qimage, there is a 30 day free trial. Just got my new Canon printer and quite impressed. Hence all the reading on printing lately, best half hour you will spend :)
http://www.ddisoftware.com/qimage/quality/