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Title: What method does Qimage use when downsizing an image? Post by: HerrBill on August 16, 2020, 11:34:39 AM I have been taught, never to throw away pixels when downsizing an image. Consequently, I never used the 'resample feature' in image resize and regularly sent images to Qimage which greatly exceed the native dpi of my Epson P600 printer. The results are excellent with no apparent loss of sharpness.
I wonder what happens under the lid of the Qimage? Can anybody enlighten me? Bill Title: Re: What method does Qimage use when downsizing an image? Post by: admin on August 16, 2020, 12:44:00 PM Any interpolation method can both upsample and downsample. Downsampling has the advantage that you have more than one pixel to determine the value of each pixel in the output so it is very accurate. The only problem is that you can end up with aliasing if you have repeating fine details in the original (moire patterns on roof shingles for example) because that detail is beyond the output resolution and is higher than the "sampling frequency" of your new output resolution. To prevent that, you have to filter out patterns that will be higher than the chosen output resolution and that is done with a gaussian filter, and that is the reason there is an anti-aliasing slider in Qimage's final print sharpening options: Edit, Preferences, Printing Options.
Regards, Mike Title: Re: What method does Qimage use when downsizing an image? Post by: HerrBill on August 16, 2020, 07:05:22 PM Thanks, Mike, for your detailed reply. When I first purchased Qimage Ultimate I set up the edit, preferences, printing options and promptly forgot all about them, so obviously I was doing the right thing all along. Your reply provoked me to revisit your tutorial and I have now refreshed my settings.
Thanks again for your assistance. Bill |