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#21
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New mandate needed
On 2012-03-23 21:44 , Eric Stevens wrote:
On Fri, 23 Mar 2012 16:16:08 -0500, David wrote: Eric writes: On Fri, 23 Mar 2012 10:02:04 -0500, David wrote: For nearly all photos (not for SI specifically, but preparing my photos for web display in general) I try for the point where extra size doesn't bring extra goodness. I understand that. Unfortunately I seem to prefer larger photographs, often with lots of detail, and trying to preserve the visual impact in an image of small size becomes very difficult. I may have to force my brain to appreciate a different syle of image. Yes, if you're doing stuff that really needs to be a few feet across, often it doesn't look it's best at 1200 pixels, I do agree . I guess that's why I bought a 19" printer. :-) Me too. But it has nothing to do with preparing an image for the SI. -- "I was gratified to be able to answer promptly, and I did. I said I didn't know." -Samuel Clemens. |
#22
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New mandate needed
On 2012-03-23 21:46 , Eric Stevens wrote:
On Fri, 23 Mar 2012 17:13:43 -0400, Alan Browne wrote: On 2012-03-22 19:08 , Eric Stevens wrote: On Thu, 22 Mar 2012 15:35:13 -0400, Alan Browne wrote: On 2012-03-22 00:21 , Eric Stevens wrote: This time I wasn't going to be first to make this last point, but I have said it previously. The maximum image size (what is it, 1200 x 800?) is fine by me but depending on the subject, this can lead to JPEGs ranging from 200kB to around 2MB. If you don't believe me, try it. I have a continual battle with file size and image quality and I don't believe 2 MB. I've since posted an example. Fair enough. I've since posted the same photo at 1200x800 and 300 kB. (Actually a little larger). Even with a high amount of detail in the image I rarely see anything above 500 kB or so. Reducing the quality level to 8 or 7 (PS CS5 scale) is usually enough. I have submitted some at quality level 6 with little or no discernible quality loss. I'm sorry that's meaningless to non-CS users like me. See below. Display it smaller as well as at a lower quality level. 1200x800 is arbitrary. And quite large compared to how most photos are shown on the web. But are the photographs intended only to be adequate on the web? Perhaps that's my problem? I'm trying to give an impression of what it might be like in a print. I've demonstrated that your photo can easily be edited to 1200x800, 300 kB and be quite presentable (it should be noted that there is nothing particularly great about the image whether at full quality or lesser. It is "large" in JPG terms because of the patterns in the image. If you don't use PS you can use any other editor. The JPG quality scales (depending on the particular app) is typically 1 ... 10, 1...12, 1...100 all with the same relative meaning/effect. In the end they all have the same basic result: a smaller file and usually (in the upper range) little or no discernible photo degradation. That's where we disagree. You disagree. Most every one else has no issue preparing to the requirement. Indeed what you represented as a 2 MB image too difficult to reduce to 300 kB for a 1200x800 image was in fact more than 2x larger in dimension with a geometric effect on file size. It's as if you don't even grasp the basic mechanics of the issue. -- "I was gratified to be able to answer promptly, and I did. I said I didn't know." -Samuel Clemens. |
#23
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New mandate needed
On 2012-03-23 21:53 , Eric Stevens wrote:
On Fri, 23 Mar 2012 17:36:27 -0400, Alan Browne wrote: On 2012-03-23 17:13 , Alan Browne wrote: On 2012-03-22 19:08 , Eric Stevens wrote: On Thu, 22 Mar 2012 15:35:13 -0400, Alan Browne wrote: On 2012-03-22 00:21 , Eric Stevens wrote: This time I wasn't going to be first to make this last point, but I have said it previously. The maximum image size (what is it, 1200 x 800?) is fine by me but depending on the subject, this can lead to JPEGs ranging from 200kB to around 2MB. If you don't believe me, try it. I have a continual battle with file size and image quality and I don't believe 2 MB. I've since posted an example. Fair enough. I've since posted the same photo at 1200x800 and 300 kB. (Actually a little larger). Sorry, I take that back. The 2 MB image was in fact 2560x1712 pixels. When reduced to 1200 x 803 and saved at "max quality" comes out to 700 kB. A slight reduction in quality gets it to 300 kB. Yet you have just written "In the end they all have the same basic result: a smaller file and usually (in the upper range) little or no discernible photo degradation." In my experience, that slight reduction in quality can often take the edge off an image and turn it from 'Gee Whiz' to 'Ho Hum'. Disagree. In fact you should know the basic photo editing effect that reducing in size increases the appearance of edge sharpness. This is certainly the case in your poor contrast, less than crisp puddy-cat photo. -- "I was gratified to be able to answer promptly, and I did. I said I didn't know." -Samuel Clemens. |
#24
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My idiosyncratic understanding of "threading" [was New mandate needed]
"Eric Stevens" wrote in message ... On Fri, 23 Mar 2012 16:16:08 -0500, David Dyer-Bennet wrote: Eric Stevens writes: On Fri, 23 Mar 2012 10:02:04 -0500, David Dyer-Bennet wrote: For nearly all photos (not for SI specifically, but preparing my photos for web display in general) I try for the point where extra size doesn't bring extra goodness. I understand that. Unfortunately I seem to prefer larger photographs, often with lots of detail, and trying to preserve the visual impact in an image of small size becomes very difficult. I may have to force my brain to appreciate a different syle of image. Yes, if you're doing stuff that really needs to be a few feet across, often it doesn't look it's best at 1200 pixels, I do agree . I guess that's why I bought a 19" printer. :-) Regards, Eric Stevens Leads me to exhort you hair-splitters and personal-parts-rubbers to Change the freaking thread Subject title. Please. -- Frank ess |
#25
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New mandate needed
On Sat, 24 Mar 2012 10:20:54 -0400, Alan Browne
wrote: On 2012-03-23 21:44 , Eric Stevens wrote: On Fri, 23 Mar 2012 16:16:08 -0500, David wrote: Eric writes: On Fri, 23 Mar 2012 10:02:04 -0500, David wrote: For nearly all photos (not for SI specifically, but preparing my photos for web display in general) I try for the point where extra size doesn't bring extra goodness. I understand that. Unfortunately I seem to prefer larger photographs, often with lots of detail, and trying to preserve the visual impact in an image of small size becomes very difficult. I may have to force my brain to appreciate a different syle of image. Yes, if you're doing stuff that really needs to be a few feet across, often it doesn't look it's best at 1200 pixels, I do agree . I guess that's why I bought a 19" printer. :-) Me too. But it has nothing to do with preparing an image for the SI. That is slowly dawning on me. Regards, Eric Stevens |
#26
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New mandate needed
On Sat, 24 Mar 2012 10:24:22 -0400, Alan Browne
wrote: On 2012-03-23 21:46 , Eric Stevens wrote: On Fri, 23 Mar 2012 17:13:43 -0400, Alan Browne wrote: On 2012-03-22 19:08 , Eric Stevens wrote: On Thu, 22 Mar 2012 15:35:13 -0400, Alan Browne wrote: On 2012-03-22 00:21 , Eric Stevens wrote: This time I wasn't going to be first to make this last point, but I have said it previously. The maximum image size (what is it, 1200 x 800?) is fine by me but depending on the subject, this can lead to JPEGs ranging from 200kB to around 2MB. If you don't believe me, try it. I have a continual battle with file size and image quality and I don't believe 2 MB. I've since posted an example. Fair enough. I've since posted the same photo at 1200x800 and 300 kB. (Actually a little larger). Even with a high amount of detail in the image I rarely see anything above 500 kB or so. Reducing the quality level to 8 or 7 (PS CS5 scale) is usually enough. I have submitted some at quality level 6 with little or no discernible quality loss. I'm sorry that's meaningless to non-CS users like me. See below. Display it smaller as well as at a lower quality level. 1200x800 is arbitrary. And quite large compared to how most photos are shown on the web. But are the photographs intended only to be adequate on the web? Perhaps that's my problem? I'm trying to give an impression of what it might be like in a print. I've demonstrated that your photo can easily be edited to 1200x800, 300 kB and be quite presentable (it should be noted that there is nothing particularly great about the image whether at full quality or lesser. It is "large" in JPG terms because of the patterns in the image. If you don't use PS you can use any other editor. The JPG quality scales (depending on the particular app) is typically 1 ... 10, 1...12, 1...100 all with the same relative meaning/effect. In the end they all have the same basic result: a smaller file and usually (in the upper range) little or no discernible photo degradation. That's where we disagree. You disagree. Most every one else has no issue preparing to the requirement. Indeed what you represented as a 2 MB image too difficult to reduce to 300 kB for a 1200x800 image was in fact more than 2x larger in dimension with a geometric effect on file size. It's as if you don't even grasp the basic mechanics of the issue. That was the result of a quick grap at example files without doing sufficient checking. But I wanted to make the point. That the effect of which I complaining is real is shown by SavageDucks two versions of the half-dome. Regards, Eric Stevens |
#27
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New mandate needed
On Sat, 24 Mar 2012 12:08:17 +0000, Pete A wrote:
Actually, Preview is a crap image scaler. Up to and including OS-X 10.5 (Leopard), image scaling in Preview, Safari, Finder thumbnail view, and other applications is not gamma corrected. I don't yet know if this error has been fixed in later versions of OS-X. http://www.4p8.com/eric.brasseur/gamma.html Thanks for that link! It's a very nice exposition of the problem, with good examples. I think that this situation has started to improve over the last couple of years (when I first heard it discussed.) In particular, Preview in OS-X 10.7 (Lion) passes the grey-Lama test with flying colours. Sadly, none of the web browsers I have on this system (Safari, Firefox, Chrome) do it properly, though. I guess that in browsers, speed trumps correctness. Unfortunately, the image scaler in NX2 is not gamma corrected either, therefore I have no means of downsizing an image without losing quality, irrespective of the JPEG compression level. What does NX2 do if you do the scaling on the RAW/NEF image (which is linear), rather than a JPEG? Rather than faffing around trying to find proper image scaling software I'll experiment with OS-X Lion - if its version of Preview has an accurate image scaler I shall be very pleased indeed. Prepare for slight/moderate pleasedness... Cheers, -- Andrew |
#28
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New mandate needed
On 2012-03-24 22:30:41 +0000, Andrew Reilly said:
On Sat, 24 Mar 2012 12:08:17 +0000, Pete A wrote: Actually, Preview is a crap image scaler. Up to and including OS-X 10.5 (Leopard), image scaling in Preview, Safari, Finder thumbnail view, and other applications is not gamma corrected. I don't yet know if this error has been fixed in later versions of OS-X. http://www.4p8.com/eric.brasseur/gamma.html Thanks for that link! It's a very nice exposition of the problem, with good examples. I think that this situation has started to improve over the last couple of years (when I first heard it discussed.) In particular, Preview in OS-X 10.7 (Lion) passes the grey-Lama test with flying colours. Thanks for the feedback, Andrew. I'm glad to hear Lion Preview will solve my problem. I wrote my own image viewer many years ago, which gave me a good understanding of image processing. I opted for speed over correctness so it would run fast enough on the old and relatively slow CPUs around at the time. My compiler predates the MMX and SSE CPU instructions so I've never updated the viewer. Sadly, none of the web browsers I have on this system (Safari, Firefox, Chrome) do it properly, though. I guess that in browsers, speed trumps correctness. I'm surprised that Safari (at least) doesn't have an option to select either speed or correctness. Unfortunately, the image scaler in NX2 is not gamma corrected either, therefore I have no means of downsizing an image without losing quality, irrespective of the JPEG compression level. What does NX2 do if you do the scaling on the RAW/NEF image (which is linear), rather than a JPEG? NX2 data in the editing steps is not linear, it's in the working space colour profile, which is what causes the problem in the scaler (and some other editing functions). Adobe Photoshop used to work this way also, but it was eventually changed to work correctly by using linear image data. BTW, I do my testing with 16-bit TIFFs. Rather than faffing around trying to find proper image scaling software I'll experiment with OS-X Lion - if its version of Preview has an accurate image scaler I shall be very pleased indeed. Prepare for slight/moderate pleasedness... Thanks again. |
#29
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New mandate needed
On 2012-03-24 16:27 , Eric Stevens wrote:
That the effect of which I complaining is real is shown by SavageDucks two versions of the half-dome. Not really. The options include reducing the size of the image you submit (where needed to overcome re-sizing limits). -- "I was gratified to be able to answer promptly, and I did. I said I didn't know." -Samuel Clemens. |
#30
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New mandate needed
On Sun, 25 Mar 2012 11:19:19 -0400, Alan Browne
wrote: On 2012-03-24 16:27 , Eric Stevens wrote: That the effect of which I complaining is real is shown by SavageDucks two versions of the half-dome. Not really. The options include reducing the size of the image you submit (where needed to overcome re-sizing limits). That has nothing to do with the point I was trying to make: that the perceptual quality of the image suffers if you reduce the amount of visual information either by reducing the size (in pixels) or by increasing the JPEG compression. Robert Coe expressed this very clearly in Message-ID: when he wrote: "I don't use Photoshop, but I don't have any trouble cropping or re-sizing an image. The editor I do use does it just fine. But re-sizing isn't the problem; it's tuning the size and quality to make maximum use of the rather restrictive (by today's standards) file size limit. And yes, it's easy to see, even on a computer screen, the differences between different levels of JPEG compression. (I feel a bit silly pointing that out to members of this group, but some people talk as though they don't really believe it.) Reaching that sweet spot is a time-consuming, iterative process. I know of no editor that lets you say, "Find me the best combination of size and quality that comes in as close as possible to 300KB." But my real point is that the SI is the *only* situation in which I ever have to do that. In all other circumstances, what's wanted is an image of a certain size and quality (usually the highest available of the latter), and the the file size will be what it will be. When you're as busy as I am (or as poor a time manager as I am, take your pick), the time spent iterating on the file size can have an impact on your willingness to participate in a given month. Note that I'm not lobbying to get the size limit changed; I'm just trying to provide an honest answer to Eric's question." My question was: "Perhaps we should conduct a survey "What is preventing or discouraging you from contributing to the SI?" .... and Roberts original answer was: "That said, what I've found most frustrating when I have participated is the time it takes to get my pictures down to the maximum accepted size while maintaining a level of quality sufficient to make the effort worthwhile." The problem is not getting the image down to fit within the size limits of SI but retaining an acceptable quality while doing so. You might be tempted to reply "some of us can do it so you should to learn how to do it as well". My point is (again) it all depends upon the type of image you wish to submit. Savageduck has provided two excellent examples of the effects of data reduction on the quality of a complex image. First (when "big is appropriate" http://homepage.mac.com/lco/filechut...me_0954BWc.jpg Second http://homepage.mac.com/lco/filechut...e_0954BWcw.jpg My feeling is that even though the smaller image may still be 'acceptable' it loses considerably to the larger _and_more_detailed_ image. That kind of thing matters to me, and apparently to Robert Coe. I accept that it might not matter to others. I'm not trying to argue for open season on file size. I'm just trying to say I would appreciate more room than at the present. Regards, Eric Stevens |
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