Relative to Kens comment about using larger format film; if you don't have the camera to achieve the larger format I suppose you could make a high quality enlargement to say 8X10 film from the 4X5 and scan that. While there would be some loss from the original 4X5 it might be small and manageable, but a significant gain over a 4X5 direct scan at 2400 spi. Has anyone done this and seen a real increase in detail?
Nate Potter, Austin TX.
If you're going to go to all that trouble, just shoot 8x10 in the first place!Originally Posted by Nathan Potter
I scan 4x5 at 4800 DPI on the 4990 (target: JPG), and then immediately downsize to 2400. (Photoshop > Image Size > 50% > Bilinear). The resulting 2400 DPI file is much cleaner than if you scan at 2400. I see zero image quality improvement by scanning at 16bit (as long as you do your color correction pre-scan), but a gigantic reduction in speed.
8x10 I scan at 2400 DPI. I'm not willing to wait for 4800 on 8x10, as the small improvement in noise is not worth the time. With a 16x20 lambda print, 8x10 is indistinguishable from 4x5 as scanned using my method... Though you can see it in the file.
Out of curiosity do you see zero quality improvement of 16-bit at the print or just the screen?
I don't know of any monitors that display in a 16-bit color depth though I may be wrong.
Also if you're printing on light sensitive paper (RA-4 I believe the process is called), I'm pretty sure those machines are limited to 8-bit so you wouldn't see any difference there, assuming you did your corrections at the scan.
However, if the OP will be doing much tweaking in PS or printing from from an ink based printer, 16-bit is probably the way to go.
The advantages of 16-bit are seen when you capture and adjust in the bigger color space.
You can always down-sample to 8-bit (or let the device drivers do it) when printing.
I'm a big skeptic about scanning to 16bit.
There is so much noise inherent to scanned film in the form of film grain and scanner noise that bit depth can become irrelevant.
See the attached. Three images: A, B, C. All three are from a single 4000 DPI Adobe RGB 35mm film scan. All have been converted to sRGB and had pretty aggressive Curve and Saturation adjustments (see screenshot).
- One of the images is the original 32bit (8 bits per color channel) scan.
- One of the images is a 15 bit version. Each channel has been exported to a 5 bit GIF (!) and re-imported. Each color channel has only 32 values instead of 256. The entire image has only 32,768 possible color values instead of 16.7 million.
- One of the images is an 8 bit GIF re-imported. The entire image has only 256 colors!
All three were color corrected at 4000 DPI, then resized for this forum (650 pixels) using Bilinear interpolation.
Here are the 100% crops from the same, along with the "straight" version without color correction.
Can anyone figure out which is the 32bit, 15bit and 8bit image?
The difference would be far more subtle with a large format image, because the noise would be oversampled that much more.
I submit that if you can't tell the difference between a 16.7 million color image and a 256 color version even after applying color correction, then there's not much point in scanning at 16 bit.
Here are the histograms for the raw (non-color corrected) images, in order from 8 bit to 32 bit.
Despite massive gaps in the histogram, all three images look good, even at 100%. They would all make excellent prints.
The combination of inherent noise and oversampling when scanning LF eliminates any theoretical advantage of higher bit depths. Quantization error (which is what people are trying to avoid by scanning at 16 bits per color channel) is, in my opinion, totally irrelevant.
Ben, could you repeat the same test with continuous tone areas like sky and water that don't have inherent texture? My experience is consistent with Ken's post. Perhaps the advantage of the higher bit depth in your example is masked by the skin and brick texture in this image.
No offense but I think we need a second and third party to perform the same above tests and let's have a full gammut of colors with a full array of graduated tones and densities in the image. Also, is anyone available to view the final prints?
Go for it
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