Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Robert Boire on January 25, 2011, 06:15:18 pm
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Hi,
I have a image taken under low light conditions (F 5, 1/80s,IS0 3200). After processing and sharpening in ACR, I convert to JPEG for printing in Photoshop. When the image opens up in Photoshop at the default scaling (25%) everything looks fine. However if I zoom just a bit, what I see on the screen becomes extremely grainy. Even as little as 25.1%. Does this make sense? Other images taken under normal lighting conditions do not display this.
Thanks
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What camera? What settings for sharpening and noise reduction? Depending on the camera, ISO 3200 could need a LOT of noise reduction. Also understand you are looking at the image on a low resolution device. What does the image look like at 100%?
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Canon T2i;
Sharpness 140, Radius 1, Detail 99,Masking 0;
No noise reduction. Though I played with it in ACR and it did not seem to do much of anything. On the other hand it looked not to bad in ACR at other zoom factors.
In as much as the image looks ok at 25%, awful at 25.1%, well it looks extremely grainy at 100%.
What I do not get is the "step" change in quality by changing the zoom factor 0.1%. It does not seem to be logical.
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Some of it could be due to the video card trying to render the image at screen resolution. There are certain sizes where it just fails. You should expect graininess at full resolution especially if you didn't use noise reduction. What size are you printing it at?
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What size are you printing it at?
I did a test print at 8.5x11. No obvious graininess or noise.
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Hi,
I have a image taken under low light conditions (F 5, 1/80s,IS0 3200). After processing and sharpening in ACR, I convert to JPEG for printing in Photoshop. When the image opens up in Photoshop at the default scaling (25%) everything looks fine. However if I zoom just a bit, what I see on the screen becomes extremely grainy. Even as little as 25.1%. Does this make sense? Other images taken under normal lighting conditions do not display this.
Thanks
When you converted and saved was it at the best quality. I remember years ago using Paint shop Pro. The default setting for saving wasn't at the best setting, about half and all of my images ended up being saved at a level that wasn't best for optimum printing. :(
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Canon T2i;
Sharpness 140, Radius 1, Detail 99,Masking 0;
No noise reduction. Though I played with it in ACR and it did not seem to do much of anything. On the other hand it looked not to bad in ACR at other zoom factors.
In as much as the image looks ok at 25%, awful at 25.1%, well it looks extremely grainy at 100%.
What I do not get is the "step" change in quality by changing the zoom factor 0.1%. It does not seem to be logical.
You have used an extreme initial sharpening routine in ACR that is guaranteed to give awful looking results on the screen - and certainly also at larger print sizes with oversharpening artifact - and will accentuate the grain insanely!
For a high-ISO image such as this, I'd start with Sharpness ~50, Detail ~25, and Masking set to a point at which accentuation of noise in smooth areas is greatly reduced. At 3200, this may take a Masking level of 25-50. Then add a bit of luminance noise reduction if printing larger - eg 15-20 - to take the edge off the noise in smooth areas without unduly affecting detail.
Pete
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Are you viewing the image on the screen at 25.1%? That may be the problem in that the image has to be mangled to that incremental display.
Best bet is to look at the image at 100%, 50%, 25%, something that makes it easy for the video card to render. Even 33%, 66%, etc. is marginal as far as optimal image viewing. Stick with the canned zooms inside PS and your image will look fine.
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Bad resampling.
Video card has nothing to do with resampling.
Jacopo
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It's the viewing size, there is nothing wrong with your image or your screen. Any "odd" viewing size will often look bad, so it's best to make critical judgements at 100% or 50% or maybe 25%, but not any in-between sizes.
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open GL may be casuing the scaling problems, try with it off. found under preferences.
s
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Canon T2i;
Sharpness 140, Radius 1, Detail 99,Masking 0;
No noise reduction.
If you are actually setting Amount for 140 and Detail 99, you are vastly oversharping. As another person mention, take those numbers down. You MUST view images at 100% inside of Camera Raw when adjusting the sharpening settings. Also note that for ISO 3200, you sure better be using some noise reduction. That's what it's there for, high ISO shots.
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Well thanks for the various suggestions.
non conventional viewing size...sampling... sharpening... and the winner (or in this case loser) is.... sharpening
First let me say that I made a mistake in my previous post. My sharpening settings in the offending version were in fact Sharpness 51, Radius 2.5 and Detail 25, not the oversharpend (140, 1,99) that I originally indicated. I must have been looking at something else.
Anyways, I reset the (51,2.5,25) to the ACR defaults (25,1,25) and reconverted to jpeg (at the maximum quality,which is what I used for the offending version) keeping all other modifications as is. The graininess that I saw in the original jpeg at factors greater than 25% effectively disappeared.
Using "normal" (33%, 50%) settings or "odd" (25.1, 26%) settings for the zoom factor did not seem to make any difference whatsoever on either the original image (normal settings did not improve the graininess) or the revised image (odd setting did not degrade the graininess).
Note that when I look at the original Raw image in PS before conversion to jpeg, I do not see any issues. So the culprit seems to be sharpening+subsequent conversion to jpeg. Effectively the less the sharpening, the clearer it is.
Nevertheless i still find the degradation from 25 to 26% in the original version a bit odd...
Thoughts anyone?