Christopher_Campbell
03-05-2005, 05:42 PM
I've been using Photokit Sharpener very successfully this past year, and it has always done everything I could have asked. Now, however, I've just purchased a wide format printer (an HP 130nr), and need assistance on an appropriate workflow for enlarging the occasional Canon 20D frame to the full printable size of this printer, which would be almost 24 x 36". After working through Bruce's Real World Camera Raw, processing in ACR at native resolution and applying capture sharpening is no problem, and I've long since developed a feel for analyzing my images and determining the appropriate settings according to subject edge frequency.
I realize that there is a considerable divergence of opinion about interpolating file for large prints (I've read most of the threads on the subject in this forum), but with my Epson 1280, I have tended to follow Bill Atkinson's advice that it is better to use Photoshop to get the data up to the Epson rasterization value of 360 ppi, and so have used Bicubic Smoother to upsample my files when I wanted to print them 13 x 19". On a fast G4, my 16-bit 20D files would bloom from 47 to 166 MB, which is big, but still entirely manageable. Then using Photokit to output sharpen the upsampled files has produced superbly detailed and sharp prints on the 1280 when printed at 2880 dpi.
Thinking about a print size as large as 24 x 36" from an 8 MP camera is obviously a somewhat more difficult problem. The native resolution of the 20D, 2336 x 3504, can only provide just under 100 ppi of actual data at that size. I did a test today in which I upsampled a crop (roughly 1/9th of the image) by 3X at 300 ppi (the rasterization value of the HP 130), which is precisely equivalent to the conditions of upsampling the full frame to 24 x 36". When I then applied Output Sharpening (Inkjet 300 Glossy) to the file, and previewed the effect on the screen, it appeared that the sharpening effect was relatively minimal, probably because the action was intended to be used on actually captured pixels, not pixels manufactured by interpolation. So what to do?
At 100 ppi, I'm way below the lowest Output Sharpening set (Inkjet 180), so it doesn't look as though I should capture sharpen at native resolution and then interpolate up (or not). I printed out the test section, and it looks definitely soft (suprise, surprise!). However, my instinct is that with certain files where I'm using very careful technique ? big tripod, Canon's best primes, mirror lockup, remote release, moderate apertures to balance MTF and diffraction ? there ought to be a way to get a satisfying large print. Looking at the test print section, my feeling is that everything will fall into place once the sharpening is pushed a little harder, but I'm just not sure how to go about it.
Thanks in advance, Christopher Campbell
I realize that there is a considerable divergence of opinion about interpolating file for large prints (I've read most of the threads on the subject in this forum), but with my Epson 1280, I have tended to follow Bill Atkinson's advice that it is better to use Photoshop to get the data up to the Epson rasterization value of 360 ppi, and so have used Bicubic Smoother to upsample my files when I wanted to print them 13 x 19". On a fast G4, my 16-bit 20D files would bloom from 47 to 166 MB, which is big, but still entirely manageable. Then using Photokit to output sharpen the upsampled files has produced superbly detailed and sharp prints on the 1280 when printed at 2880 dpi.
Thinking about a print size as large as 24 x 36" from an 8 MP camera is obviously a somewhat more difficult problem. The native resolution of the 20D, 2336 x 3504, can only provide just under 100 ppi of actual data at that size. I did a test today in which I upsampled a crop (roughly 1/9th of the image) by 3X at 300 ppi (the rasterization value of the HP 130), which is precisely equivalent to the conditions of upsampling the full frame to 24 x 36". When I then applied Output Sharpening (Inkjet 300 Glossy) to the file, and previewed the effect on the screen, it appeared that the sharpening effect was relatively minimal, probably because the action was intended to be used on actually captured pixels, not pixels manufactured by interpolation. So what to do?
At 100 ppi, I'm way below the lowest Output Sharpening set (Inkjet 180), so it doesn't look as though I should capture sharpen at native resolution and then interpolate up (or not). I printed out the test section, and it looks definitely soft (suprise, surprise!). However, my instinct is that with certain files where I'm using very careful technique ? big tripod, Canon's best primes, mirror lockup, remote release, moderate apertures to balance MTF and diffraction ? there ought to be a way to get a satisfying large print. Looking at the test print section, my feeling is that everything will fall into place once the sharpening is pushed a little harder, but I'm just not sure how to go about it.
Thanks in advance, Christopher Campbell