dgktkr Posted December 18, 2015 Share #41 Posted December 18, 2015 Advertisement (gone after registration) Ah, the unbelievers ! I shot a newspaper page with my M240 and I can perfectly read the fine text on the M240 screen. Then I extracted the 1472x976 preview JPEG embedded in the resulting DNG, and the text is totally unreadable. Why would the camera not display the full-resolution data contained in the DNG ? Give me a reason that makes sense. How did you do that, if I may ask? I'd like to examine preview images in the DNGs generated by a couple of cameras I have. dgktkr Link to post Share on other sites More sharing options...
Advertisement Posted December 18, 2015 Posted December 18, 2015 Hi dgktkr, Take a look here Quality of enlarged photos in DNG format.. I'm sure you'll find what you were looking for!
ramarren Posted December 18, 2015 Share #42 Posted December 18, 2015 How did you do that, if I may ask? I'd like to examine preview images in the DNGs generated by a couple of cameras I have. dgktkr I use EXIFtool. On the command line: > exiftool -b -PreviewImage {filename}.DNG > {filename}-preview.JPG Link to post Share on other sites More sharing options...
CheshireCat Posted December 18, 2015 Share #43 Posted December 18, 2015 How did you do that, if I may ask? I'd like to examine preview images in the DNGs generated by a couple of cameras I have. I use the exiftool command line app on my Mac. CD to your image folder and type: exiftool -a -b -W %d%f_%t%-c.%s -preview:all . This will extract all types of embedded preview images, for each image in that folder. Enjoy Link to post Share on other sites More sharing options...
CheshireCat Posted December 18, 2015 Share #44 Posted December 18, 2015 I use EXIFtool. On the command line: > exiftool -b -PreviewImage {filename}.DNG > {filename}-preview.JPG This will only work for some type of raw files and embedded images. Please use the cmd in my previous post. Link to post Share on other sites More sharing options...
Steve Spencer Posted December 18, 2015 Share #45 Posted December 18, 2015 Ah, the unbelievers ! I shot a newspaper page with my M240 and I can perfectly read the fine text on the M240 screen. Then I extracted the 1472x976 preview JPEG embedded in the resulting DNG, and the text is totally unreadable. Why would the camera not display the full-resolution data contained in the DNG ? Give me a reason that makes sense. You are still reading the file on very different screens. I displayed a picture I shot with my iPhone on its screen and it looked great text was totally readable then I viewed it on my 50 inch UHD television and it looks like crap. Jaggies all over the place. It wasn't really readable. Would that shock anyone? That is exactly the type of thing you are doing. The embedded JPEG is no doubt optimized for the screen on the M240--as it should be because that is where it is going to be displayed and only there--why is it surprising it doesn't look nearly as good when it is blown up way larger than it is intended to be? Link to post Share on other sites More sharing options...
CheshireCat Posted December 18, 2015 Share #46 Posted December 18, 2015 You are still reading the file on very different screens. Steve, I know what you are talking about, but that is not the case. If a text character takes 2x2 pixels in the embedded image then it is not readable even on the M240 LCD. You know, the M240 LCD cannot magically invent pixels that are not there. ... and you did not answer my question... Link to post Share on other sites More sharing options...
Steve Spencer Posted December 19, 2015 Share #47 Posted December 19, 2015 Advertisement (gone after registration) Steve, I know what you are talking about, but that is not the case. If a text character takes 2x2 pixels in the embedded image then it is not readable even on the M240 LCD. You know, the M240 LCD cannot magically invent pixels that are not there. ... and you did not answer my question... Of course the M240 LCD cannot invent pixels, and no one is saying that. The question is how an image looks on a screen and what that proves. I maintain that just because the image looks better on the M240 LCD vs. a large computer screen does not mean that the M240 is using a larger image. You are saying that demonstration proves the M240 is using a larger image. I say I am not convinced. The answer to your question is simple. It takes my iMac 5K a non-trivial amount of time to convert a DNG file to the resolution of the M240 screen. The tiny by comparison computer in the M240 simply does not have the computing power to convert the file. Why would they do that anyway? The medium JPEG is plenty to review a file on the tiny LCD on the M240, and they can use that. You can check that out by saving a medium jpeg on the SL and we know it is not converting the DNG file and still that medium JPEG does quite well on the SL LCD (but not so much on the much higher res EVF). Why would they add all that computing overhead to transform the DNG? Link to post Share on other sites More sharing options...
CheshireCat Posted December 19, 2015 Share #48 Posted December 19, 2015 The answer to your question is simple. It takes my iMac 5K a non-trivial amount of time to convert a DNG file to the resolution of the M240 screen. The tiny by comparison computer in the M240 simply does not have the computing power to convert the file. That is the answer I expected, and in fact it is wrong. The tiny chip in the M240 has been created to process images, while your iMac is a general purpose computer. A general purpose computer, can be orders of magnitude slower than a tiny chip optimized to do only a single specialized task. When you shoot a photo, the RAW data from the sensor are converted to RGB in a fraction of a second to be displayed on the RGB LCD, and - if enabled - to be also compressed into a full-resolution JPEG file (another compute-intensive operation your Mac takes "forever" to do, but the tiny chip can do quite fast). All these operations your chip can do in about 300 milliseconds. Now, the very same RAW data from the sensor are saved to a DNG file on the card. The chip does not care if the RAW data come from the sensor or form the card; all that matters is it can convert RAW to RGB quite fast. Other camera chips are way faster than the Maestro in the M240, but it seems to be fast enough for most M shooters Link to post Share on other sites More sharing options...
Steve Spencer Posted December 19, 2015 Share #49 Posted December 19, 2015 That is the answer I expected, and in fact it is wrong. The tiny chip in the M240 has been created to process images, while your iMac is a general purpose computer. A general purpose computer, can be orders of magnitude slower than a tiny chip optimized to do only a single specialized task. When you shoot a photo, the RAW data from the sensor are converted to RGB in a fraction of a second to be displayed on the RGB LCD, and - if enabled - to be also compressed into a full-resolution JPEG file (another compute-intensive operation your Mac takes "forever" to do, but the tiny chip can do quite fast). All these operations your chip can do in about 300 milliseconds. Now, the very same RAW data from the sensor are saved to a DNG file on the card. The chip does not care if the RAW data come from the sensor or form the card; all that matters is it can convert RAW to RGB quite fast. Other camera chips are way faster than the Maestro in the M240, but it seems to be fast enough for most M shooters That is just the answer that I expected from you too. Without any evidence or documentation you call others wrong. It is also why I didn't bother to answer your question the first time. I sort of thought you would just say I was wrong and you wouldn't back it up. Let's just say we disagree. I think the M240 uses the medium JPEG that is embedded in the DNG and you think it uses the full DNG file. You think your demonstration of extracting the medium JPEG file and finding that it isn't that clear on a much bigger monitor proves they use the whole DNG and I do not. You think the M240 can very quickly process the DNG and I do not. I still have a question for you, however. Why does the M240 embed the medium JPEG if it doesn't use it? Link to post Share on other sites More sharing options...
CheshireCat Posted December 19, 2015 Share #50 Posted December 19, 2015 Why does the M240 embed the medium JPEG if it doesn't use it? Main reason is that all computers can display JPEG, and they can do it fast. Another reason is that cameras also take advantage of the embedded JPEG, as it can be displayed quickly without loading the entire image from the card. Of course, like I have explained, if the user zooms in the picture a couple levels to see the details, then the camera will use the raw data in the DNG and you will notice a little delay while the DNG file is loaded and converted to RGB for display. You think that the M240 can very quickly process the DNG and I do not. Actually, you think, while I know. Link to post Share on other sites More sharing options...
Steve Spencer Posted December 19, 2015 Share #51 Posted December 19, 2015 Main reason is that all computers can display JPEG, and they can do it fast. Another reason is that cameras also take advantage of the embedded JPEG, as it can be displayed quickly without loading the entire image from the card. Of course, like I have explained, if the user zooms in the picture a couple levels to see the details, then the camera will use the raw data in the DNG and you will notice a little delay while the DNG file is loaded and converted to RGB for display. Actually, you think, while I know. Wow! Since you know everything and I know nothing perhaps you will be willing to enlighten all of us with actual references to what you know, but perhaps you can't be bothered to condescend to actually document your pronouncements and we will just have to take them as gospel sent down from Mount Olympus. The reason that I talk about things as "I think" is that I would like to have a civil discussion where I treat others as equals rather than take a high handed approach in which I pronounce I am right and they are wrong and that I know the answers and they obviously don't. If you want to have such a civil discussion then I am glad to continue. If you want to provide sources for your information then that is great too. If you want to describe the logic of your decision that would be much appreciate. When you just say others are wrong or that you know the answers and others don't, then that is not much of a conversation. So far the only "evidence" that you have provided for your position is that when you extracted the embedded medium JPEG it didn't look as good on a large monitor. I found and find that total unconvincing. If you have any other evidence or documentation or logic in support of your position I would in all sincerity like to see it, but please drop the high handed pronouncements about what you know and that others are wrong. Link to post Share on other sites More sharing options...
thighslapper Posted December 19, 2015 Share #52 Posted December 19, 2015 Give up, Steve ........ Mr Cat is always right and has powers of self conviction that would defeat anyone less resilient than a superhero. Just be thankful for the American people that he is not a Politician ...... Link to post Share on other sites More sharing options...
pop Posted December 19, 2015 Share #53 Posted December 19, 2015 It's like this. On the M (Typ 240) the DNG image includes a JPG preview image. The preview image is something like 580 kB in size and holds 1472 x 976 pixels. The DNG image itself holds, of course, 5976 × 3992 pixels. This is a complete picture as taken with an M (Typ 240) and merely shrunk to a size allowed by the forum. I have taken the image some time ago and moved to the SD card in the camera for this test. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! This is what the DNG file looks like when viewed on the M at maximum magnification. This is a photograph of an actual M showing the picture. When I extract the preview image from the DNG file and blow it up so that is has the same apparent size it looks like this: As a matter of fact, the preview image is much smaller. The same part of that picture viewed at a magnification of 100% looks like this: Hence: the camera actually shows the "raw" data from the DNG when viewing the image on its display, at least when showing the image magnified. This quite obvious as it shows details on the camera's display that are not present in the preview image but only in the raw data (or in the full size JPG file which is absent from the camera). In this case, it's the song, not the singer. Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! This is what the DNG file looks like when viewed on the M at maximum magnification. This is a photograph of an actual M showing the picture. When I extract the preview image from the DNG file and blow it up so that is has the same apparent size it looks like this: As a matter of fact, the preview image is much smaller. The same part of that picture viewed at a magnification of 100% looks like this: Hence: the camera actually shows the "raw" data from the DNG when viewing the image on its display, at least when showing the image magnified. This quite obvious as it shows details on the camera's display that are not present in the preview image but only in the raw data (or in the full size JPG file which is absent from the camera). In this case, it's the song, not the singer. ' data-webShareUrl='https://www.l-camera-forum.com/topic/254437-quality-of-enlarged-photos-in-dng-format/?do=findComment&comment=2952226'>More sharing options...
pop Posted December 19, 2015 Share #54 Posted December 19, 2015 This is the 100% crop of the actual image: Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/254437-quality-of-enlarged-photos-in-dng-format/?do=findComment&comment=2952232'>More sharing options...
J S H Posted December 20, 2015 Share #55 Posted December 20, 2015 This is the 100% crop of the actual image: L1002131.JPG The Cat is right of course. Pop was kind enough to demonstrate for the slow learners. It's not too hard to figure out that the M240 is drawing from the actual DNG as you zoom in...what else would it be doing for those long seconds of waiting time? Link to post Share on other sites More sharing options...
Steve Spencer Posted December 20, 2015 Share #56 Posted December 20, 2015 The Cat is right of course. Pop was kind enough to demonstrate for the slow learners. It's not too hard to figure out that the M240 is drawing from the actual DNG as you zoom in...what else would it be doing for those long seconds of waiting time? As the obvious slow learner here, I appreciate the demonstration. Keep in mind that the M240 is unusual in displaying the RAW file when viewing on the display. The approach of the SL--viewing an appropriate JPEG is much more common and that is why some of us needed the demonstration. Personally, I am glad that the SL did not continue this approach as I do not appreciate slow review times and in my view this would be particularly annoying on a very responsive camera like the SL. Of course others might have preferred the approach of the M240, but I like that I can decide what type of preview image I want and even change some parameters of what it looks like. Link to post Share on other sites More sharing options...
J S H Posted December 20, 2015 Share #57 Posted December 20, 2015 As the obvious slow learner here, I appreciate the demonstration. Keep in mind that the M240 is unusual in displaying the RAW file when viewing on the display. The approach of the SL--viewing an appropriate JPEG is much more common and that is why some of us needed the demonstration. Personally, I am glad that the SL did not continue this approach as I do not appreciate slow review times and in my view this would be particularly annoying on a very responsive camera like the SL. Of course others might have preferred the approach of the M240, but I like that I can decide what type of preview image I want and even change some parameters of what it looks like. On the other hand, I would much prefer that the SL used the same approach as the M240. The overhead of dealing with the unwanted but necessary jpegs could be eliminated with what would likely be just an extra second or two of wait time for the much faster processor of the SL to render the DNG. Also, you can definitely change the parameters of the M240 preview, even to the extent of choosing the color of filter (red, green, etc) to fine tune the B&W preview image. The ideal implementation on the SL would be to let the user decide. Unfortunately, that was not the path taken by Leica. Link to post Share on other sites More sharing options...
Steve Spencer Posted December 20, 2015 Share #58 Posted December 20, 2015 On the other hand, I would much prefer that the SL used the same approach as the M240. The overhead of dealing with the unwanted but necessary jpegs could be eliminated with what would likely be just an extra second or two of wait time for the much faster processor of the SL to render the DNG. Also, you can definitely change the parameters of the M240 preview, even to the extent of choosing the color of filter (red, green, etc) to fine tune the B&W preview image. The ideal implementation on the SL would be to let the user decide. Unfortunately, that was not the path taken by Leica. Sounds like a good request for a firmware upgrade. Link to post Share on other sites More sharing options...
thighslapper Posted December 20, 2015 Share #59 Posted December 20, 2015 One of the biggest moans about the M ...... in all its versions ......... was speed, speed, speed ........ as a processor the camera was crap and it did nothing quickly in comparison to its peers. Leica have solved that with the Q & SL and in many cases overtaken some of the competition. Even if going back to displaying the DNG has only a small time overhead I would prefer usage to be as slick and fast as possible ...... and the lower card capacity with DNG+JPG and having to selectively download only DNG from the card is a small price to pay..... Link to post Share on other sites More sharing options...
FMB Posted December 22, 2015 Author Share #60 Posted December 22, 2015 Sounds like a good request for a firmware upgrade. + 1 Francisco Link to post Share on other sites More sharing options...
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