How I prevent blown areas

This is a discussion on How I prevent blown areas within the Do's and Dont's forums, part of the Photography Tips category; Originally Posted by Henry Peach One thing to keep in mind when shooting raw. The histogram is based on an in-camera processed jpeg. That means ...


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  1. #11
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    Quote Originally Posted by Henry Peach View Post
    One thing to keep in mind when shooting raw. The histogram is based on an in-camera processed jpeg. That means in-camera processing parameters will affect how the histogram looks, but that is not how the raw file will look. For instance higher contrast, saturation, and sharpening can show blown out highlights on the camera histogram that won't be a problem with the actual raw file. I set my cameras to the most neutral, most processing turned off processing parameters as possible. That way I get the most accurate histogram possible. Even so I usually find that I can recover highlight detail in the raw processor that the camera histogram showed as blinkies because they are just slightly over the edge of the histogram (in camera).
    Is this the case for all cameras, like there is some technical reason why a RAW cannot generate a histogram? I'm not producing a JPEG file at all, just a RAW. So is the histogram based on the JPEG preview?

    Also, I agree. The first thing people should do once they own a camera that shoots RAW is to consider JPEG only for web display. The idea of using a JPEG as a capture just format astounds me, especially today when a 4gb card will cost only about $25.
    bear with me. i don't have an escape button...

  2. #12

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    Quote Originally Posted by twinkle_turnip View Post
    Is this the case for all cameras, like there is some technical reason why a RAW cannot generate a histogram? I'm not producing a JPEG file at all, just a RAW. So is the histogram based on the JPEG preview?
    A raw file is just data. It's not even a specific file format, but rather a descriptive term. It's the "raw" data off the sensor in a mostly unprocessed form. It's like exposed, but undeveloped film. There is no picture. Before an image can be seen it must be processed into some sort of image file that can be viewed such as a tiff or jpeg. When you see an image first pop up in the raw processing software that's your raw data that's been processed with whatever the software's default processing is, or it's the embedded jpeg thumbnail the in-camera software came up with.

    All digital cameras shoot raw, even those that don't offer "raw" as a setting. If the camera is set to jpeg it sends the raw data to the in-camera processing software, and only saves the finished jpeg. If the camera is set to raw it saves the raw data as is, and then processes a jpeg thumbnail to go with it.

    Raw vs jpeg is not one kind of file vs another kind of file. Raw vs jpeg is out-of-camera processing software vs in-camera processing software. There's nothing wrong with jpegs. The problem is with the processing software.
    "I donít use an exposure meter. My personal advice is: Spend the money you would put into such an instrument for film. Buy yards of film, miles of it. Buy all the film you can get your hands on. And then experiment with it. That is the only way to be successful in photography. Test, try, experiment, feel your way along. It is the experience, not technique, which counts in camera work first of all. If you get the feel of photography, you can take fifteen pictures while one of your opponents is trying out his exposure meter." -Alfred Eisenstaedt

  3. #13
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    Quote Originally Posted by Henry Peach View Post
    There's nothing wrong with jpegs.
    Well, except that JPEG is 8 bit and in RAW you can choose a 16 bit output format and that JPEG is a lossy compression, and you will loose some amount of detail from that, and even if this damage is negligible, it will become more apparent as the photo is edited, even modestly as jpeg often uses shadows or gradients to "hide" compression... Sure, if there were a in-camera processor that could read your mind and know how you intend the scene to look, there wouldn't be any issue between the two....
    bear with me. i don't have an escape button...

  4. #14

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    I admit that I always process in 16 bit raw, tiff or psd, and my last step is conversion to an 8 bit jpeg for the lab/web. The only time I've noticed the difference between processing in 16 bit and 8 bit is if I'm trying to save a pretty screwed up exposure. In the regular processing most of my photos get it doesn't make a difference. If my computer had any problems handling the larger files I'd use 8 bit tiffs without worry (before this latest computer that is the way I did it).

    I also try not to process and re-save jpegs. I think that is the right attitude to have. On the other hand I took a workshop where they did a demonstration in which they made a 16"x20" print. Then they opened, slightly edited, and re-saved the same jpeg over and over at less than max quality. It took a dozen re-saves before artifacts became noticeable pixel peeping. They stopped at 25 re-saves, made another print, and invited us to come up and stick our noses against it. In real world prints we weren't able to spot the difference. The point being that while jpeg loss/compression is something to be concerned with, jpegs aren't as fragile as they are often made out to be. It's possible to break them, but you've almost got to try. I think the folks who should shoot jpegs are the folks who liked slides. They don't want to mess with much processing anyway; they won't be editing and re-saving it more than once or twice.

    I'm not trying to encourage folks to be sloppy. It's good to understand how it's supposed to be done. There are times though that it's nice to know that a shortcut isn't going to hurt the image. I use Smugmug for sharing my family photos. When I started out I was uploading full res, max quality jpegs, because that's they way it's supposed to be done! Of course the upload time was killing me. So I tried a radical experiment (radical for me). I reduced the resolution to 250ppi @ 8"x12", and saved the jpeg at quality 8 ( GASP! ). I cut the file size to about 1/10th what it was, and the prints look just as good. I wouldn't order a 20"x30" from those files, but my family isn't going bigger than 8x12 anyway.

    I do not like the results that I get when my cameras are set to jpeg. Even beyond technical issues the typical in-camera processing is too Velvia-esque for my taste. But I blame the software, and I do think that someday I'll be able to upload my favorite ACR/LR pre-sets into my DSLR, and use Adobe in-camera processing. I haven't done a lot of comparisons between my Canon DSLRs set to jpeg vs raw, but in the comparisons I've done with my Canon point-n-shoot the differences are striking. Even with the processing parameters set to neutral and as much sharpening and noise compression turned off as possible the jpegs come out of the camera horribly artifact ridden! It's disgusting how it destroys detail! I loaded CHDK so I could access the raw files, and at low ISOs they look fantastic after I process them. I think almost all of the complaints about the "digital look" can be blamed on poor processing. I'll post some examples sometime.

    If you are using a Canon point-n-shoot check this out http://chdk.wikia.com/wiki/CHDK


    "I donít use an exposure meter. My personal advice is: Spend the money you would put into such an instrument for film. Buy yards of film, miles of it. Buy all the film you can get your hands on. And then experiment with it. That is the only way to be successful in photography. Test, try, experiment, feel your way along. It is the experience, not technique, which counts in camera work first of all. If you get the feel of photography, you can take fifteen pictures while one of your opponents is trying out his exposure meter." -Alfred Eisenstaedt

  5. #15
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    I'm not saying that jpeg doesn't have it's place, but it's place is not a working file. I do not doubt that some images will be visually indistiguishable when jpegged at higher qualities. However, other images will suffer much more readily. Having worked at the Maine Photographic Workshops I can deffenitely see an instructor specifically choosing an image which is best suited to illustrate the idea, especially in today's sloppy, anti-pixel sniffing environment

    Images with lots of gentle gradiants will band much more quickly in 16 bit, shadow detail is much more compressed. For finished work, jpeg might be sufficient. But because jpeg by it's adaptive nature will be unpredictable, and because it can be easy to miss artifacts and banding on the screen, I cannot recommend anyone use jpeg except, perhaps, as a finished product.

    Nothing sucks more when you've spent all day working on an image only to find that those subtle variations in the shadows can't be emphasized without nasty banding artifacts because your image is trapped in an 8 bit jpeg and lacks the tonal fidelity. Because you don't Oalways know how you're going to process something, it's best to keep all your options available.

    I can appreciate the anti-pixel sniffing movement. However, I am still unconvinced in many cases. You wouldn't shoot 110 format, iso 400 kodak royal gold and expect 6x7 Astia. Just like you shouldn't expect 20mp uncompressed 16 bit TIFF quality and flexibility from an 8mp jpeg. This doesn't mean that jpegs or 110 film doesn't have it's uses, or that good images can't be made using an 8mp image, only that there are limitations that should be considered.
    bear with me. i don't have an escape button...

  6. #16

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    You don't have to convince me, I've always been a believer in raw.

    100% crop from snapshot. Canon G7 jpeg with processing parameters set to neutral, sharpening, and noise reduction turned off as much as possible. Finished processing in Canon DPP.


    100% crop from snapshot. Canon G7 raw (using CHDK as G7 doesn't normally offer raw). Processing done in Adobe Camera Raw.



    Notice the difference in the hair detail. Some folks may point out that the raw image is noisier, but at 8"x12" which is the largest this snap would ever get printed that noise would be invisible. I didn't use any luminance NR, but if I thought the noise would be a problem I could have or used other NR software. I would have control over the NR, and could avoid those nasty artifacts. I probably oversharpened it a bit too (I get sloppy trying to catch up on the family snaps). The artifacts and destruction of detail in the jpeg would be visible in an 8"x12" print. I think bad, in-camera jpeg processing is the main cause of the complaints people have about the look of digital photographs.

    I've never really used the jpeg setting on my DSLRs, so maybe in-camera processing is better, but until I started shooting raw with the point-n-shoots I thought they all sucked. If only the dang thing would take a photo when I push the button I'd almost be happy.


    "I donít use an exposure meter. My personal advice is: Spend the money you would put into such an instrument for film. Buy yards of film, miles of it. Buy all the film you can get your hands on. And then experiment with it. That is the only way to be successful in photography. Test, try, experiment, feel your way along. It is the experience, not technique, which counts in camera work first of all. If you get the feel of photography, you can take fifteen pictures while one of your opponents is trying out his exposure meter." -Alfred Eisenstaedt


 
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