09-27-2011, 07:02 PM
[quote name='jenbenn' timestamp='1317122526' post='11896']
For purley technical purposes it of course doent make sense. For practical purposes it makes a lot sense. Since no one enjoys his photos at the mp dependet (relativ) 100% view but at an absolute size you can only compare two cameras meaningfully if you define a common output size. Only therby you can tell which camera allows for better print/screen quality at say 50x75 cm.
[/quote]
But there is a big problem with downscaling. With downscaling you can not predict how the "noise" and the detail will behave/survive. Different sized images get downscaled different percentages, giving different results.
So, it is just wrong to do so for measurements.
If you want to test for same size prints, you will have to actually print them at the same size, without first down sampling the pixels to varying degrees. Else you are just "testing" down sampling algorithms....
For purley technical purposes it of course doent make sense. For practical purposes it makes a lot sense. Since no one enjoys his photos at the mp dependet (relativ) 100% view but at an absolute size you can only compare two cameras meaningfully if you define a common output size. Only therby you can tell which camera allows for better print/screen quality at say 50x75 cm.
[/quote]
But there is a big problem with downscaling. With downscaling you can not predict how the "noise" and the detail will behave/survive. Different sized images get downscaled different percentages, giving different results.
So, it is just wrong to do so for measurements.
If you want to test for same size prints, you will have to actually print them at the same size, without first down sampling the pixels to varying degrees. Else you are just "testing" down sampling algorithms....