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Wrong exposure when scanning truncated negative film (Nikon Coolscan V ED)
On Fri, 24 Sep 2010 04:38:54 -0700 (PDT), Castor Nageur
wrote: snip * Please tell if you know a simpler/easiest way ? Thanks in advance. I sometimes get results like that. What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Most of the time that gets me where I want to be, but you can always do additional adjustments. I did that with your image, and here is the result I get: http://www.flickr.com/photos/51646689@N00/5021459976/ It took less than a minute. |
#2
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Wrong exposure when scanning truncated negative film (Nikon CoolscanV ED)
On 9/25/2010 9:56 AM, Castor Nageur wrote:
écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. I hoped there was a way I did not found yet to auto-expose on a selected scanner area. The quality is only impacted when saving as jpg and that loss is grossly overstated. I do avoid serial jpg saves. |
#3
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Wrong exposure when scanning truncated negative film (Nikon Coolscan V ED)
In article ,
Castor Nageur wrote: rwalker écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. There's no reason to expect that an "analog" treatment would be superior to a "digital" one. There's plenty of theoretical proof of their equivalency. Isaac |
#4
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Wrong exposure when scanning truncated negative film (Nikon Coolscan V ED)
"Castor Nageur" wrote in message
... rwalker écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. I hoped there was a way I did not found yet to auto-expose on a selected scanner area. Where did you ever get that idea from? Even JPEG takes a lot of opening and reopening before you have noticeable, unintentional degradation. -- Peter |
#5
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Wrong exposure when scanning truncated negative film (Nikon CoolscanV ED)
On 25/09/2010 22:46, Peter wrote:
"Castor Nageur" wrote in message ... rwalker écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. I hoped there was a way I did not found yet to auto-expose on a selected scanner area. Where did you ever get that idea from? Even JPEG takes a lot of opening and reopening before you have noticeable, unintentional degradation. Actually I did some tests and as long as you don't change JPEG compression parameters and don't perform global edits (color balance, contrast and such) there is no degradation at all even with very high compression. -- Bertrand |
#6
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Wrong exposure when scanning truncated negative film (Nikon Coolscan V ED)
"Ofnuts" wrote in message
... On 25/09/2010 22:46, Peter wrote: "Castor Nageur" wrote in message ... rwalker écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. I hoped there was a way I did not found yet to auto-expose on a selected scanner area. Where did you ever get that idea from? Even JPEG takes a lot of opening and reopening before you have noticeable, unintentional degradation. Actually I did some tests and as long as you don't change JPEG compression parameters and don't perform global edits (color balance, contrast and such) there is no degradation at all even with very high compression. Your statement is consistent with my understanding. Except that any time pixels are dropped and restored the restoration is based upon assumptions that may not be accurate. The way I understand it is that the compression-decompression algorithm makes assumptions about the color of the adjacent pixels and drops a lot of the pixels that duplicate the ones that are kept. (If the sky is blue on one location, nearby locations will also have a blue sky.) When you change the adjacent pixels, the original assumptions are no longer valid and there is degradation upon restoration. OK gearheads! My above statement oversimplifies the problem. So you are free to attack my statement and explain the algorithm in plain English, so even I can understand the theory. -- Peter |
#7
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Wrong exposure when scanning truncated negative film (Nikon Coolscan V ED)
In article ], isw
writes In article , Castor Nageur wrote: rwalker écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. There's no reason to expect that an "analog" treatment would be superior to a "digital" one. There's plenty of theoretical proof of their equivalency. Show me the theoretical proof that digital processing a scan which has been underexposed by several stops, due to the missing part of the frame in this case upsetting the scanner auto-exposure, is in any way "equivalent" in quality to correctly exposing it in the first place. If your claim was in any way true there would be no need for scanners to have more than 1-bit ADC resolution, since it would be possible to extract the full dynamic range, colour depth and signal to noise ratio by digitally processing that single bit image. -- Kennedy Yes, Socrates himself is particularly missed; A lovely little thinker, but a bugger when he's ****ed. Python Philosophers (replace 'nospam' with 'kennedym' when replying) |
#8
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Wrong exposure when scanning truncated negative film (Nikon CoolscanV ED)
On 25/09/2010 23:47, Peter wrote:
"Ofnuts" wrote in message ... On 25/09/2010 22:46, Peter wrote: "Castor Nageur" wrote in message ... rwalker écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. I hoped there was a way I did not found yet to auto-expose on a selected scanner area. Where did you ever get that idea from? Even JPEG takes a lot of opening and reopening before you have noticeable, unintentional degradation. Actually I did some tests and as long as you don't change JPEG compression parameters and don't perform global edits (color balance, contrast and such) there is no degradation at all even with very high compression. Your statement is consistent with my understanding. Except that any time pixels are dropped and restored the restoration is based upon assumptions that may not be accurate. There are no "assumptions", only computations :-) The way I understand it is that the compression-decompression algorithm makes assumptions about the color of the adjacent pixels and drops a lot of the pixels that duplicate the ones that are kept. (If the sky is blue on one location, nearby locations will also have a blue sky.) When you change the adjacent pixels, the original assumptions are no longer valid and there is degradation upon restoration. Everything happens in a 8x8 block. The contents of a block are totally immune from the content of the adjacent blocks. And if nothing changes in the block, the re-computation yields the very same numbers than the contents of the block where decoded from. OK gearheads! My above statement oversimplifies the problem. So you are free to attack my statement and explain the algorithm in plain English, so even I can understand the theory. Check Wikipedia. More than you want to know -- Bertrand |
#9
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Wrong exposure when scanning truncated negative film (Nikon Coolscan V ED)
In article , Castor Nageur
writes rwalker écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. I hoped there was a way I did not found yet to auto-expose on a selected scanner area. Just turn the auto-exposure off and use a fixed, if necessary manually adjusted, exposure for the entire roll of film. The reason that the CS-V has 14-bit ADC is to accommodate the huge dynamic range of slide film. Colour negative film has nowhere near that dynamic range, little over 2D, and this will easily fit within the 4.2Dmax of the scanner, irrespective of any exposure errors on the original film image itself. If it was slide film, or non-chromagenic B&W, that you had this problem with then there would be no work around to the manual exposure, since slide film utilises the entire density range of the scanner. However, with colour negative film, autoexposure for each frame is just a waste of scan time. -- Kennedy Yes, Socrates himself is particularly missed; A lovely little thinker, but a bugger when he's ****ed. Python Philosophers (replace 'nospam' with 'kennedym' when replying) |
#10
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Wrong exposure when scanning truncated negative film (Nikon Coolscan V ED)
On Sat, 25 Sep 2010 17:47:40 -0400, "Peter"
wrote: "Ofnuts" wrote in message ... On 25/09/2010 22:46, Peter wrote: "Castor Nageur" wrote in message ... rwalker écrivait : What I do is to crop the image, and in Photoshop elements, I do, in order, auto contrast, auto color correct, auto levels. Applying 3 successive image processing will decrease the picture quality. I was thinking of an analogical treatment instead of a digital one. I hoped there was a way I did not found yet to auto-expose on a selected scanner area. Where did you ever get that idea from? Even JPEG takes a lot of opening and reopening before you have noticeable, unintentional degradation. Actually I did some tests and as long as you don't change JPEG compression parameters and don't perform global edits (color balance, contrast and such) there is no degradation at all even with very high compression. Your statement is consistent with my understanding. Except that any time pixels are dropped and restored the restoration is based upon assumptions that may not be accurate. The way I understand it is that the compression-decompression algorithm makes assumptions about the color of the adjacent pixels and drops a lot of the pixels that duplicate the ones that are kept. (If the sky is blue on one location, nearby locations will also have a blue sky.) When you change the adjacent pixels, the original assumptions are no longer valid and there is degradation upon restoration. OK gearheads! My above statement oversimplifies the problem. So you are free to attack my statement and explain the algorithm in plain English, so even I can understand the theory. Trying to re-educate you on all your wrong assumptions would be like trying to explain physics to a slug in a garden--pointless and not worth anyone's time. |
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