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#31
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Compression in JPEG files in digital cameras
HEMI-Powered wrote:
OK, but again, Thomas, I interpreted the OP as being a fairly new digital owner and thus a novice on file types, so I just mentioned TIFF as an alternative if their camera supports it. TIFF is universally recognized, although news readers cannot decode it in line, and about its only drawback other than large size is that if you want to save EXIF, you cannot use LZW compression, or at least AFAIK. Hardly any cameras support TIFF. Yes, you can use EXIF with LZW ... the are completely unrelated as far as TIFF is concerned. I don't want to start yet another religious war about bit-length. It seems to me, though, that 16-bit color - no matter where it comes from or in what format(s) it is saved to - is a subject for VERY advanced people who have software that can correctly manipulated it. And, the person behind the camera and behind the keyboard also has to be quite a bit more knowledgeable to gain any real advantage over 8-bit. It doesn't take VERY advanced to use 16-bit. Anybody who wants to shoot camera RAW should understand a workflow that [potentially] uses 16-bit image manipulation. But, I have a question for you Thomas: everytime 16-bit color comes up, part of the raging debate is that most/all cameras and apps, including PS CS2, really only have 11 or 12 bits of real information, the others being basically just noise that is ignorned by the software. Has that improved in ANY format, whether it be JPEG, TIFF, or RAW? i.e., is something closer to 16-bit or true 16-bit now available for them with deep pockets? If so, could you just give me 25 words or less as a heads-up on today's status so I can go looking? Yes, I know Google is my best friend, but on things like this, it is like the old saying "I don't even know enough to ask an intelligent question", and it goes to the extreme frustration I have had for well over a year trying to find a RAW for Dummies kind of book that isn't keyed to PS CS2 or Elements that will at least get me started up the learning curve. You don't get more information by converting a 12-bit RAW file to a 16-bit TIFF (or PSD). You would definitely lose information if you converted to an 8-bit TIFF and you would lose even more information if you converted to an 8-bit JPEG (all JPEG images are 8-bit). As far as the benefits of a 16-bit workflow, I will leave that for another discussion which has been hashed about here before and is available in many books and online resources. In any event, I find these threads fascinating but always feel bad for the poor OP who has some simple or easy question like he does the size of the image or compression cause image problems? I kinda doubt that level of knowledge is ready for all of the sophisticated answers the more experienced folks have been bantering about. Yes, /I/ learn something, but a rank novice just gets totally snowed under and may feel so intimidated as to not even come back for a 2nd round of questions. The simple answer to a "simple" question is "yes". But, if you want to know why, then you have to read. -- Thomas T. Veldhouse We have more to fear from the bungling of the incompetent than from the machinations of the wicked. |
#32
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Compression in JPEG files in digital cameras
Thomas T. Veldhouse added these comments in the current
discussion du jour ... Hardly any cameras support TIFF. Yes, you can use EXIF with LZW ... the are completely unrelated as far as TIFF is concerned. I stand/sit corrected, Thomas! I just tried an LZW TIFF from PSP 9. It gave me a warning that no EXIF would be saved, but in fact, it was. I reopened it and all my Rebel data was there along with a comment to an editable field. Thanks for letting me know about this- I always stopped when I saw the warning. I don't want to start yet another religious war about bit-length. It seems to me, though, that 16-bit color - no matter where it comes from or in what format(s) it is saved to - is a subject for VERY advanced people who have software that can correctly manipulated it. And, the person behind the camera and behind the keyboard also has to be quite a bit more knowledgeable to gain any real advantage over 8-bit. It doesn't take VERY advanced to use 16-bit. Anybody who wants to shoot camera RAW should understand a workflow that [potentially] uses 16-bit image manipulation. I said I don't want to start any religious wars, and I will not. But, going from 8-bit software to 16-bit costs money I don't want to spend, and my personal skill level is woefully inadequate to know what to do with 16-bit, much less RAW. In this NG, people run the gamut from rank novices to very advanced amateurs to pros, with all types and prices of cameras, and software as simple as Irfanview or as complex, expensive, and difficult to learn as PS CS. So, /I/ do not think that making the jump to either 16-bit or RAW is at all trivial. I take nothing away from you or anyone who's mastered it, but sometimes we humans forget the difficulties we had the the steepness of the learning curve. I would've long ago gone to RAW if I could find even ONE book that explained how to properly use it that was NOT aimed specifically at PhotoShop. There is no straight-forward way I know of to translate the workflow into PSP 9. I do not like how Corel mangled PSP X and PSP XI, so have not gone to them. I will probably cut over to PS Elements when I get my next computer, but that most likely is a year away. So, I would ask you or anyone implying that 16-bit and RAW are simple to learn to consider the needs, wants, and time budget of us lesser homo sapiens. Thank you. But, I have a question for you Thomas: everytime 16-bit color comes up, part of the raging debate is that most/all cameras and apps, including PS CS2, really only have 11 or 12 bits of real information, the others being basically just noise that is ignorned by the software. Has that improved in ANY format, whether it be JPEG, TIFF, or RAW? i.e., is something closer to 16-bit or true 16-bit now available for them with deep pockets? If so, could you just give me 25 words or less as a heads-up on today's status so I can go looking? Yes, I know Google is my best friend, but on things like this, it is like the old saying "I don't even know enough to ask an intelligent question", and it goes to the extreme frustration I have had for well over a year trying to find a RAW for Dummies kind of book that isn't keyed to PS CS2 or Elements that will at least get me started up the learning curve. You don't get more information by converting a 12-bit RAW file to a 16-bit TIFF (or PSD). You would definitely lose information if you converted to an 8-bit TIFF and you would lose even more information if you converted to an 8-bit JPEG (all JPEG images are 8-bit). As far as the benefits of a 16-bit workflow, I will leave that for another discussion which has been hashed about here before and is available in many books and online resources. You didn't quite answer my question. What I am curious about is if any cameras or scanners can output a FULL 16-bit color bitmap and are there any apps that can process all 16 across their entire function/tool/feature set. I understand the loss if a 12- bit RAW is downgraded to 8-bit anything, especially JPEG, so I'm still in inquisative mode. Now, I have never met anyone who didn't think their own pictures could be made better. I've not asked you, but then, we don't know each other well. But, I use both the 80/20 Rule and the Law of Diminshing Returns to govern how much time and effort to devote to any editing task. Some of my car pictures are easy enough to do in a few minutes, most are in the 15-20 minute range, and a sizable enough number get into 30, 60, more. Since I am a documentary rather than a creative or artistic photographer of cars, I have many other interests than spending all day on a small series of cars shot at an outdoor show or museum with or without flash. Again, people hereabouts run a really wide gamut of skills, but much more importantly, not everybody wants, much less needs, all the sophistication. My daughter, for example, does just a quicky crop and resame down and takes here SD card to Meijer to print 4x6. That's all she wants. I can't argue with her logic even though I disagree because she's an adult who has the freedom to do what she pleases with her time and money. In any event, I find these threads fascinating but always feel bad for the poor OP who has some simple or easy question like he does the size of the image or compression cause image problems? I kinda doubt that level of knowledge is ready for all of the sophisticated answers the more experienced folks have been bantering about. Yes, /I/ learn something, but a rank novice just gets totally snowed under and may feel so intimidated as to not even come back for a 2nd round of questions. The simple answer to a "simple" question is "yes". But, if you want to know why, then you have to read. /I/ know that both size and compression have a greater or lesser effect on final technical quality, but did the OP in this thread? His OP was down so low in the grass, he wanted just a simple recommendation as to how to start taking "good" pictures, and never came back - I don't think - to even clarify his criteria for "good". -- HP, aka Jerry |
#33
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Compression in JPEG files in digital cameras
David J Taylor added these comments in the current discussion du
jour ... Both ordinary JPEG and TIFF are both 8-bit. I only mentioned TIFF, either the uncompressed kind or LZW, as an alternative to the OP or any lurkers who want a simpler lossless file system than RAW, OK, I appreciate that. David, occasionally, I save to simple Windows BMP or maybe PNG, and on rare occasions, I will save to PSP's proprietary pspimage format. Which goes to my constand wonder if the OP ever gets much out of a thread when it suddenly gets quite technical, well into theory and away from pragmatics, and we all have fun but I think they shake their head and slink away. Can't prove that, I just "feel" it. Yes, David, as recently as this spring as I was getting ready for the summer car show season. It isn't that I dispute you at all, you're much more skilled and knowledgeable than me, it is that MY experience shows that the amount of work necessary to get an 8 MP image down to my 1.5 MP finished size without introducing aliasing and other undesirable non-compression artifacts just isn't worth my time and effort. I never revisited the lower quality, i.e., higher compression, option on my Rebel because I could easily see JPEG compression artifacts at a large enough percentage that I didn't want to risk blowing otherwise good pictures. As you and others have so correctly pointed out, memory is so cheap, that it really doesn't matter if the image is 500KB or one meg. Yes, I would expect that when using less than the native resolution of the camera, the images will be slightly sharper (meaning that there are fewer pixels covering a black-white transition), and therefore more likely to show JPEG artefacts at a particular compression (quality) level. So when using lower resolution, stick with the highest JPEG quality. Makes sense to me, anyhow! Again, not for you David because you understand what I try to do and why, but for them lurkers, about 99 44/100% of my images are only displayed with a screensaver or slide show in Windows and/or posted to Usenet. That is why I seldom save larger than 1400 x 1050 and never larger than 1600 x 1200. That said, I'm well aware of what happens with that low a PPI trying to print to borderless 8.5 x 11 glossy paper, but it does satisfy my needs. And, I have found that Windows and common slide show programs that "pixel resize" rather than mathematically "resample" for speed of display totally mangles an image much larger than my current 1280 x 960 monitor. Now, I do have plans to upgrade to a 24" or 26" LCD about the time I get my next PC built, maybe late next year, so I will experiment with the higher resolutions images at that time. One other comment wrt posting to Usenet. I simply do not have the time to save at a large size for myself but resample smaller to post, therefore I also do not have the time and energy to "do it right" so as to minimize inevitible aliasing of fine details on the chrome, badgees, and character lines of my car pictures in order to meet NG FAQs. It all boils down to this: each of us should do what works best for us, and I believe you support that notion. I do stray into "contrarian" mode with novices, though, because I can tell by their meager OP that they've been snared by the marketing hype that more mega pixels means better pictures, without regard to the dozens of other factors involved. Thanks for your observations and have a great week! -- HP, aka Jerry |
#34
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Compression in JPEG files in digital cameras
HEMI-Powered wrote:
I said I don't want to start any religious wars, and I will not. But, going from 8-bit software to 16-bit costs money I don't want to spend, and my personal skill level is woefully inadequate to know what to do with 16-bit, much less RAW. In this NG, people run the gamut from rank novices to very advanced amateurs to pros, with all types and prices of cameras, and software as simple as Irfanview or as complex, expensive, and difficult to learn as PS CS. So, /I/ do not think that making the jump to either 16-bit or RAW is at all trivial. I take nothing away from you or anyone who's mastered it, but sometimes we humans forget the difficulties we had the the steepness of the learning curve. I would've long ago gone to RAW if I could find even ONE book that explained how to properly use it that was NOT aimed specifically at PhotoShop. There is no straight-forward way I know of to translate the workflow into PSP 9. I do not like how Corel mangled PSP X and PSP XI, so have not gone to them. I will probably cut over to PS Elements when I get my next computer, but that most likely is a year away. I didn't say it was trivial. I said it doesn't require the user to be advanced. My daughter was using my computer with Adobe Lightroom on it and she picked up how to use it on her own. She is 14 and by no means a computer whiz. Further, she did it without my help, as she was editting [JPEG] files she took on her P&S. However, working with RAW and 16-bit in this environment is nearly transparent. So, I would ask you or anyone implying that 16-bit and RAW are simple to learn to consider the needs, wants, and time budget of us lesser homo sapiens. Thank you. I never once used the words "simple to learn". I said you don't have to be advanced. There are plenty of books out there on RAW workflow that are pretty good, and you are free to read them. Further, there are many websites as well, which are free for your viewing pleasure. You didn't quite answer my question. What I am curious about is if any cameras or scanners can output a FULL 16-bit color bitmap and are there any apps that can process all 16 across their entire function/tool/feature set. I understand the loss if a 12- bit RAW is downgraded to 8-bit anything, especially JPEG, so I'm still in inquisative mode. The image is FULL 16-bit color. The ADC and source sensor may or may not be 16-bit. Most modern DSLR source at 12-bit and a couple new ones claim 14-bit. My old Nikon Coolscan had a 14-bit ADC in it as well, but 16-bit was available for a premium. Moving from 12-bit to 16-bit should incur no loss, and indeed, it offers additional room for manipulation (so it is even worthwhile to convert 8-bit to 16-bit and then do your manipulations and finally convert back to 8-bit for printing or what have you). Now, I have never met anyone who didn't think their own pictures could be made better. I've not asked you, but then, we don't know each other well. But, I use both the 80/20 Rule and the Law of Diminshing Returns to govern how much time and effort to devote to any editing task. I tend to preprocess in groups. I went out to the Bad Lands of South Dakota last June followed by the Black Hills. I processed all the photos from a given session at one time in just a couple of minutes. Then I look for photos that I might like to further work with. That often happens months later BTW. I find the photo of interest and look more closely, perhaps correct for chromatic aberation if it exists, exposure, color, curves. I might even get more creative and create a composite or do some HDR work sourcing from several frames. My point though, is that the initial processing is usually quite fast and pretty high level. Some of my car pictures are easy enough to do in a few minutes, most are in the 15-20 minute range, and a sizable enough number get into 30, 60, more. Since I am a documentary rather than a creative or artistic photographer of cars, I have many other interests than spending all day on a small series of cars shot at an outdoor show or museum with or without flash. Again, people hereabouts run a really wide gamut of skills, but much more importantly, not everybody wants, much less needs, all the sophistication. My daughter, for example, does just a quicky crop and resame down and takes here SD card to Meijer to print 4x6. That's all she wants. I can't argue with her logic even though I disagree because she's an adult who has the freedom to do what she pleases with her time and money. Sounds like you are in need of a workflow. Again, I suggest a good book, but won't suggest a specific book to you at this time. I recommend you consider a RAW workflow as well, but that is up to you. /I/ know that both size and compression have a greater or lesser effect on final technical quality, but did the OP in this thread? His OP was down so low in the grass, he wanted just a simple recommendation as to how to start taking "good" pictures, and never came back - I don't think - to even clarify his criteria for "good". Perhaps he read what he needed and just lurks. Usenet threads often mutate and that is an expected occurance on USENET (or any threaded forum). -- Thomas T. Veldhouse We have more to fear from the bungling of the incompetent than from the machinations of the wicked. |
#35
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Compression in JPEG files in digital cameras
Thomas T. Veldhouse added these comments in the current
discussion du jour ... I didn't say it was trivial. I said it doesn't require the user to be advanced. My daughter was using my computer with Adobe Lightroom on it and she picked up how to use it on her own. She is 14 and by no means a computer whiz. Further, she did it without my help, as she was editting [JPEG] files she took on her P&S. However, working with RAW and 16-bit in this environment is nearly transparent. There's an old saying that covers my view on this: "the algorithm to solve this problem or that one is straigt-forward but not trivial. So, I would submit that if what you learned through the school of hard knocks you readily admit isn't trivial, it likely also is not for novices or the faint of heart. So, I would ask you or anyone implying that 16-bit and RAW are simple to learn to consider the needs, wants, and time budget of us lesser homo sapiens. Thank you. I never once used the words "simple to learn". I said you don't have to be advanced. There are plenty of books out there on RAW workflow that are pretty good, and you are free to read them. Further, there are many websites as well, which are free for your viewing pleasure. I have scoured my local bookstores and their on-line stores looking for exactly what you describe, but every one I've come across so far assumes I have either PS CS or PS Elements, while I have PSP 9 and like it. So, workflow tutorials would be quite helpful to me, but NOT when they are illustrated with photographs shot off a PhotoShop screen with the steps involved. I also have the last version of Raw Shooter Premium before Adobe bought them, killed it, and launched Lightroom. It has these really nifty 89- page manual, but it is a reference manual and assumes I already know what I want to do and why and simply tells me what tools I want. What it is NOT is a leg-up on the learning curve, which I find so steep that RAW is outside the range of my radar and sonar for time management reasons. You didn't quite answer my question. What I am curious about is if any cameras or scanners can output a FULL 16-bit color bitmap and are there any apps that can process all 16 across their entire function/tool/feature set. I understand the loss if a 12- bit RAW is downgraded to 8-bit anything, especially JPEG, so I'm still in inquisative mode. The image is FULL 16-bit color. The ADC and source sensor may or may not be 16-bit. Most modern DSLR source at 12-bit and a couple new ones claim 14-bit. My old Nikon Coolscan had a 14-bit ADC in it as well, but 16-bit was available for a premium. Moving from 12-bit to 16-bit should incur no loss, and indeed, it offers additional room for manipulation (so it is even worthwhile to convert 8-bit to 16-bit and then do your manipulations and finally convert back to 8-bit for printing or what have you). Excuse my denseness, but a "full" 16-bit image of which only 12 or 14 bits are usuable, is NOT what I meant. You just confirmed my supposition, nobody is yet actually producing images that have legitimate data in all 16 bits. Now, I have never met anyone who didn't think their own pictures could be made better. I've not asked you, but then, we don't know each other well. But, I use both the 80/20 Rule and the Law of Diminshing Returns to govern how much time and effort to devote to any editing task. I tend to preprocess in groups. I went out to the Bad Lands of South Dakota last June followed by the Black Hills. I processed all the photos from a given session at one time in just a couple of minutes. Then I look for photos that I might like to further work with. That often happens months later BTW. I find the photo of interest and look more closely, perhaps correct for chromatic aberation if it exists, exposure, color, curves. I might even get more creative and create a composite or do some HDR work sourcing from several frames. My point though, is that the initial processing is usually quite fast and pretty high level. What can I say? You're obviously better/faster than I am. I applaud you for that skill, I simply don't have it and many of my friends who are fellow car show and musueum photographers are in about the same boat as I am. Some of my car pictures are easy enough to do in a few minutes, most are in the 15-20 minute range, and a sizable enough number get into 30, 60, more. Since I am a documentary rather than a creative or artistic photographer of cars, I have many other interests than spending all day on a small series of cars shot at an outdoor show or museum with or without flash. Again, people hereabouts run a really wide gamut of skills, but much more importantly, not everybody wants, much less needs, all the sophistication. My daughter, for example, does just a quicky crop and resame down and takes here SD card to Meijer to print 4x6. That's all she wants. I can't argue with her logic even though I disagree because she's an adult who has the freedom to do what she pleases with her time and money. Sounds like you are in need of a workflow. Again, I suggest a good book, but won't suggest a specific book to you at this time. I recommend you consider a RAW workflow as well, but that is up to you. Do not asssume I have no workflow. I clearly do. In fact, to help friends that are just getting into digital photography, I have codified my workflow into 10 basic steps and about 3 pages of text. Just because I have a finite algorithm - the workflow - does NOT even begin to address the issues that confront me that take far longer. Perhaps the biggest problem stems from extremes in dynamic range tonal characteristics across the entire car or key parts of it. Simply doing a 5 minute global tweak doesn't cut it. If it did, I'd have cut my workflow to just 2 or 3 steps and been a lot happier than I am. NO, I am simply NOT going to spend time and effort, both of which are in very short supply with me, beating my head against a stone wall because people in this NG like RAW so much they become zealots. I understand the fundamental concepts and why it is better, but you and several others need to understand that not everybody is cut out for that. /I/ know that both size and compression have a greater or lesser effect on final technical quality, but did the OP in this thread? His OP was down so low in the grass, he wanted just a simple recommendation as to how to start taking "good" pictures, and never came back - I don't think - to even clarify his criteria for "good". Perhaps he read what he needed and just lurks. Usenet threads often mutate and that is an expected occurance on USENET (or any threaded forum). I think the OP here, like so many, got completely blown away from my middle-ground technical discussions and yours, blowing him out to sea with wild stories about 16-bit color and RAW when all he likely wants to do is what my daughter does - just get a fairly decent 4 x 6 prints at Meijer, she simply isn't at all interested in being an accomplished digital photographer. So, what would you say to her, that's she's just as stupid and stubborn as I am just because we have alternative views from your own? Surely some of the advanced people in this NG that get into the range of what I call elitists and image bigots must recognize that there isn't one right way to do things, there are literally hundreds of ways. EOT. -- HP, aka Jerry |
#36
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Compression in JPEG files in digital cameras
HEMI-Powered wrote:
There's an old saying that covers my view on this: "the algorithm to solve this problem or that one is straigt-forward but not trivial. So, I would submit that if what you learned through the school of hard knocks you readily admit isn't trivial, it likely also is not for novices or the faint of heart. I didn't have any trouble learning how to do it. I have drawn on several online resources and browsed a couple of books to get ideas on how to streamline my approach, but there was no attendance at the "school of hard knocks". Have it your way ... it is extremely difficult, not for the faint of heart and everybody [except extremely advanced individuals, such as myself] should just simply use JPEG ;-) I have scoured my local bookstores and their on-line stores looking for exactly what you describe, but every one I've come across so far assumes I have either PS CS or PS Elements, while I have PSP 9 and like it. So, workflow tutorials would be quite helpful to me, but NOT when they are illustrated with photographs shot off a PhotoShop screen with the steps involved. I also have the last version of Raw Shooter Premium before Adobe bought them, killed it, and launched Lightroom. It has these really nifty 89- page manual, but it is a reference manual and assumes I already know what I want to do and why and simply tells me what tools I want. What it is NOT is a leg-up on the learning curve, which I find so steep that RAW is outside the range of my radar and sonar for time management reasons. You have to have a RAW converter, and as such, it requires a workflow that uses it. The workflow using the RAW converter in PSP will be different than the workflow using the RAW converter in Adobe Lightroom and yet again different the using the RAW converter in PS and Bridge. You know what? You have the same issue with JPEG. You need to establish a workflow, plain and simple. You will find as many opinions on the best workflow as there are people who have opinions on workflow. Everybody will do it differently. Excuse my denseness, but a "full" 16-bit image of which only 12 or 14 bits are usuable, is NOT what I meant. You just confirmed my supposition, nobody is yet actually producing images that have legitimate data in all 16 bits. Yes they are. Nikon Coolscan scanners are available that are 16-bit (some lower scale images are 14-bit). More important than a 16-bit image is a 16-bit workflow. You want more data to work with and the reason should be obvious at this point. Having the room to work with it is why a 16-bit workflow has advantages over an 8-bit workflow. What can I say? You're obviously better/faster than I am. I applaud you for that skill, I simply don't have it and many of my friends who are fellow car show and musueum photographers are in about the same boat as I am. You know, I am not sure where you are trying to go with this thread. Perhaps you want to legitimize your approach by minimizing the 16-bit workflow including RAW that I mention. Be my guest. But I don't think this thread has progressed, so I am departing it. I think the OP here, like so many, got completely blown away from my middle-ground technical discussions and yours, blowing him out to sea with wild stories about 16-bit color and RAW when all he likely wants to do is what my daughter does - just get a fairly decent 4 x 6 prints at Meijer, she simply isn't at all interested in being an accomplished digital photographer. So, what would you say to her, that's she's just as stupid and stubborn as I am just because we have alternative views from your own? Surely some of the advanced people in this NG that get into the range of what I call elitists and image bigots must recognize that there isn't one right way to do things, there are literally hundreds of ways. Ask the OP's opinion on the matter. The thread moved on, as they usually do on USENET and does not and should not be constrained to a scope arbitrarily imposed by you. -- Thomas T. Veldhouse We have more to fear from the bungling of the incompetent than from the machinations of the wicked. |
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Compression in JPEG files in digital cameras
HEMI-Powered wrote:
I never revisited the lower quality, i.e., higher compression, option on my Rebel because I could easily see JPEG compression artifacts at a large enough percentage that I didn't want to risk blowing otherwise good pictures. As you and others have so correctly pointed out, memory is so cheap, that it really doesn't matter if the image is 500KB or one meg. Could you please post an impage where you can easily see JPEG artifacts at the highest quality your Rebel produces? Thanks! The reason I ask is, it's hard for me to see JPEG artifacts at Q 95 and 1x1 or 2x1 chroma subsampling, and I'm good at seeing JPEG artifacts. |
#38
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Compression in JPEG files in digital cameras
Thomas T. Veldhouse added these comments in the current
discussion du jour ... Have it your way ... it is extremely difficult, not for the faint of heart and everybody [except extremely advanced individuals, such as myself] should just simply use JPEG ;-) This is a fair statement and I respect you for recognizing that not everone can be a superstar. I also appreciate some corroboration that it is indeed some sort of "advanced" individual who makes the jump from ordinary JPEG to 16-bit or to RAW. You know, I am not sure where you are trying to go with this thread. Perhaps you want to legitimize your approach by minimizing the 16-bit workflow including RAW that I mention. Be my guest. But I don't think this thread has progressed, so I am departing it. I am not on any kind of soapbox except the First Amendment one which give me the freedom and rights to do what I think is best for me, as you do what is best for you, and all the others do the same. Ask the OP's opinion on the matter. The thread moved on, as they usually do on USENET and does not and should not be constrained to a scope arbitrarily imposed by you. I don't seek out OPs. If, for any reasons good or bad they choose not to come back in and provide more details on what they want to do and why or to simply say "hey, guys, you're having a great time but you've over my head, can you please tone it down some and just get me over the hump to some reasonable prints of my vacation this summer?" If the OP cannot or will not do that, there isn't much any of us across any skill level can do to help them. And, I understand quite well, thank you, the way that threads have a life of their own and I am attempting NO imposition of my views, except when /I/ have a question or I feel I must defend my honor. That has nothing at all to do with the OP who should take care of themselves. I will say this, though, it is a rare, rare thread in this or the SLR NG that start off with an innocent novice OP that don't wind up sooner or later into some sort of contest where people want to suggest that THEIR methods and workflows are the only way. Life just isn't that way. I've explained the purpose I use my images for enough times that I shan't repeat them here, except to say that in general, I don't personally give a rip about PPI or contest-quality images because that isn't my bag. If people cannot deal with that, it is their problem, not mine. And, so, yet another disagreement is coming to an end because I am again tired of being harangued for not wanting to be a Top Gun - the best of the best - when it comes to digital photography. I more or less live by the motto that whatever floats your boat is fine by me so long as it doesn't swamp mine. -- HP, aka Jerry |
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Compression in JPEG files in digital cameras
Bill Tuthill added these comments in the current discussion du
jour ... I never revisited the lower quality, i.e., higher compression, option on my Rebel because I could easily see JPEG compression artifacts at a large enough percentage that I didn't want to risk blowing otherwise good pictures. As you and others have so correctly pointed out, memory is so cheap, that it really doesn't matter if the image is 500KB or one meg. Could you please post an impage where you can easily see JPEG artifacts at the highest quality your Rebel produces? Thanks! The reason I ask is, it's hard for me to see JPEG artifacts at Q 95 and 1x1 or 2x1 chroma subsampling, and I'm good at seeing JPEG artifacts. This isn't a binary NG so I can't post here, but I also do not keep an accurate inventory of those images I may see artifacts in out of my camera. And, by the time I have finished with an image, I have taken the technical steps I think are prudent to eliminate all but the most minor defects by always re-opening a just-saved image to check for the two biggies: artifacts as in streaks, blobs, and blotches, or aliasing, aka jaggies. Incidently, I don't think I ever said I've seen an artifact in my Rebel's higher of its two available quality settings. What I said was that some significant percentage at the lower setting DID exhibit artifacts. There are many factors involved other than just pure over compression, but I would hazard a guess that at the lower quality level I see at least 5% that have damage, sometimes 10% or more. And, since I cannot predict at the time I am shooting which 5 or 10% will be damaged, I go for the quality. Memory is cheap, my time is not. As to Chroma subsampling, my normal setting is 1x2. I will lower the compression number and/or change to 1x1 (none) until I can eliminate the damage as described above. -- HP, aka Jerry |
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Compression in JPEG files in digital cameras
HEMI-Powered wrote:
This is a fair statement and I respect you for recognizing that not everone can be a superstar. I also appreciate some corroboration that it is indeed some sort of "advanced" individual who makes the jump from ordinary JPEG to 16-bit or to RAW. Oh ... for God's sake, it was SARCASM. -- Thomas T. Veldhouse We have more to fear from the bungling of the incompetent than from the machinations of the wicked. |
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