Scottes
14th of July 2004 (Wed), 16:56
We had a topic going, Enlarging (Interpolating) in Steps Degrades Digital Images (http://photography-on-the.net/forum/showthread.php?t=37151), and I ran a few tests comparing different results. I sent off a number of images to the printer and just got them back. These weren't test images, per se, but several different images printed at either 12x18 @ 400dpi or 8x12 @ 400dpi. Each image was upsized between 240% - 280%, depending on the crop. Each was final sharpened using USM at approximately 180% / 2.0 Radius / 0 Threshold - give or take a little.
The results in a nutshell: it depends. And from 2 feet away it doesn't really matter.
I printed a wolf that was very sharp, using a process of upsizing in 10% increments using Bicubic interpolation at every step. Original was full 3072x2048, final image was 12x18 or 4800x7200. It came out very good, but not perfect. The final print was a bit noisy (and I had run Neat Image as a first step) and I expected this after running tests discussed in the thread above. The contrasty edges of the fur looked less than perfect. However, from 2 feet away it looks great.
I used a trial of Extensis SmartScale to upsize a couple of painted turtles. Original was full, 3072x2048, and the final size was 12x18, 4800x7200. SmartScale (and Genuine Fractals) give the image a bit of a "painted" effect that looks quite weird on the screen. But the final print was excellent. I attribute this - at least in part - to the subject matter. The "painted" lines of a painted turtle against the dark grey shell lends itself to SmartScale. It's hard to describe - when I get a chance I'll post some samples.
A trial of Smartscale of the wolf looked terrible, absolutely terrible on screen, and I would not print that. Fur does not lend itself to Smartscale. I would think that images with fairly sharp transitions lines between areas of solid color would work well with Smartscale - leaves, landscapes, buildings even. But not fur or crisp feathers or other such images with high detail but snooth transitions between colors.
A picture of a sparrow that was ultra-sharp at 3072x2048 was upsized to 7200x4800. I used a process where I upsized 10% using Bicubic Smoother, did that again, then another 10% using Bicubic Sharper. I continued this 3-step process until I reached the desired size. The results were unbelievable - due at least in part to the original sharpness of the image. From a distance of 6 inches noise was barely apparent and only in a couple small places, lines were still crisp without blowing out too much contrast at edges. I feel that this is an excellent process for very finely detailed fur or feathers.
A picture of a butterfly started from 2750x1850 and went up to both 7200x4800 and 4800x3200. I used the 3-step Smoother Smoother Sharper method as I did in the sparrow above. Again the results were excellent. The original was not as sharp as the sparrow but was very good, though slightly blurry in places. The shot was at ISO 800 with Neat Image for noise removal, so I expected some noise issues after all the upsizing. However, I was quite happy with the end results - the 2 steps of Bicubic Smoother greatly reduce the harsh contrast of the noise so that the single Bicubic Sharper step doesn't blow out the noise to high contrast. I was very happy with the image, though I wasn't happy at all with the printer's crop of this shot. That's another story.
So in the end I am very happy with my 3-step method of upsizing in 10% increments using Bicubic Smoother twice followed by Bicubic Sharper. It works very well in high-detail images like fur, and if there's a concern with noise. But a nicely sharp image with no noise would probably work fine using straight Bicubic all the way. I don't think that SmartScale or Genuine Fractals are worth the money - though on some images they will produce superior results.
And, if you're more than 2 feet away it probably doesn't matter which method you use.
The results in a nutshell: it depends. And from 2 feet away it doesn't really matter.
I printed a wolf that was very sharp, using a process of upsizing in 10% increments using Bicubic interpolation at every step. Original was full 3072x2048, final image was 12x18 or 4800x7200. It came out very good, but not perfect. The final print was a bit noisy (and I had run Neat Image as a first step) and I expected this after running tests discussed in the thread above. The contrasty edges of the fur looked less than perfect. However, from 2 feet away it looks great.
I used a trial of Extensis SmartScale to upsize a couple of painted turtles. Original was full, 3072x2048, and the final size was 12x18, 4800x7200. SmartScale (and Genuine Fractals) give the image a bit of a "painted" effect that looks quite weird on the screen. But the final print was excellent. I attribute this - at least in part - to the subject matter. The "painted" lines of a painted turtle against the dark grey shell lends itself to SmartScale. It's hard to describe - when I get a chance I'll post some samples.
A trial of Smartscale of the wolf looked terrible, absolutely terrible on screen, and I would not print that. Fur does not lend itself to Smartscale. I would think that images with fairly sharp transitions lines between areas of solid color would work well with Smartscale - leaves, landscapes, buildings even. But not fur or crisp feathers or other such images with high detail but snooth transitions between colors.
A picture of a sparrow that was ultra-sharp at 3072x2048 was upsized to 7200x4800. I used a process where I upsized 10% using Bicubic Smoother, did that again, then another 10% using Bicubic Sharper. I continued this 3-step process until I reached the desired size. The results were unbelievable - due at least in part to the original sharpness of the image. From a distance of 6 inches noise was barely apparent and only in a couple small places, lines were still crisp without blowing out too much contrast at edges. I feel that this is an excellent process for very finely detailed fur or feathers.
A picture of a butterfly started from 2750x1850 and went up to both 7200x4800 and 4800x3200. I used the 3-step Smoother Smoother Sharper method as I did in the sparrow above. Again the results were excellent. The original was not as sharp as the sparrow but was very good, though slightly blurry in places. The shot was at ISO 800 with Neat Image for noise removal, so I expected some noise issues after all the upsizing. However, I was quite happy with the end results - the 2 steps of Bicubic Smoother greatly reduce the harsh contrast of the noise so that the single Bicubic Sharper step doesn't blow out the noise to high contrast. I was very happy with the image, though I wasn't happy at all with the printer's crop of this shot. That's another story.
So in the end I am very happy with my 3-step method of upsizing in 10% increments using Bicubic Smoother twice followed by Bicubic Sharper. It works very well in high-detail images like fur, and if there's a concern with noise. But a nicely sharp image with no noise would probably work fine using straight Bicubic all the way. I don't think that SmartScale or Genuine Fractals are worth the money - though on some images they will produce superior results.
And, if you're more than 2 feet away it probably doesn't matter which method you use.