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Old 05-03-2012   #111
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Default Re: Jpeg or RAW?

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Originally Posted by korman View Post
Apaflo, here you're mixing up things a little.

The main difference between a raw and a jpg without sharpening is the loss of colour information, because jpg uses only 8 bit per colour channel while raw use 12 to 16 bit. Here data is actually thrown away in the conversion and if things you want later are thrown out, they're gone.
It isn't really color information that is lost though, it's granularity in tonal range. Note that bit-depth in the RAW file has nothing at all to do with color encoding, as that is accomplished with the Bayer Color Filter Array, not with encoded bits. When data from a 14 bit RAW file is converted to an RGB image format each pixel is generated using anything from a 2x2 sensor matrix up to 4x4 or even more. Typically the minimum is actually a 3x3 matrix, so the number of bits used to generate a pixel is (9 * 14), or 126 bits. The pixel in a 16 bit RGB image has (3 * 16) bits, or 48 bits per pixel. If it is saved to an 8 bit RGB image format there are 24 bits per pixel.
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Most commonly this happens with the exposure sliders and white balance. If you convert raw with a standard profile to 16-bit TIFF, nothing really is lost and you have in TIFF the same options as in Raw.
A 16 bit TIFF image format has 48 bits per pixel. Even a 12 bit RAW file uses at least 108 bits per pixel (and usually more). So there is a significant data loss even when producing a 16 bit TIFF image.
Quote:
As far as I know, some raw-converter internally transmit 16-bit TIFF to further processing stages like image editors.
That is common, but there are other formats too. The point with all of them though is the use of an RGB gamma corrected format.
Quote:
For resizing, cropping, rotating, sharpening, noise removal, lens correction and all other things that do not affect colours, jpg is just as fine as raw.
That is absolutely not true.

What makes a difference is the granularity of the tonal levels available. Cropping and rotating do not affect the pixel values, but all of the other things you mention do. They necessarily involve expansion and contraction of tonal values, and the entire problem with a JPEG image is that it has already been reduced to a minimal granularity, and any further change that is at all significant will result in visible posterization (quantization distortion) artifacts.

Quote:
But here again, if you sharpen in camera like crazy, data is lost and can't be recovered. So it makes sense to keep the in camera processing limited to things you don't intend to do later in post processing. The ultimate case here being, not to touch the pictures at all.
I'm not sure I follow what you mean. But a couple of things to note... the effects of a high pass sharpen algorithm are reversible (with a low pass filter), but the effects of UnSharp Mask are not.

As I've said before though, you cannot produce an in camera JPEG that is exactly correct for any size other than the pixel dimensions the camera produces. A JPEG should be properly sharpened after it is resampled for the web or printing, and the camera cannot provide either.
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Old 05-03-2012   #112
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Default Re: Jpeg or RAW?

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I don't think there is any one that can accomplish all of what you described 100% of the time. If someone actually claims they can, they are full of sh@t. I'm with you on this post.
Oh, they can...

But the reason is because the standard they judge by amounts to "Is it pretty?" or "Is it good enough?", and it probably is! The fact that it could be a lot prettier or in some other way a lot better is not part of their criteria.

For other people the only question is can it be made better, because nothing is ever "good enough".

Edit: Both are quite reasonable methods...
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Old 05-03-2012   #113
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Default Re: Jpeg or RAW?

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Originally Posted by jerryph View Post
Actually, if you can...
- accurately adjust your WB in camera with every shot
- shoot without needing noise reduction in camera
- pull all the detail info from shadows that you need in camera
- get the quality sharpening that you want in camera
- cropping your pic 100% in camera
- does absolutely no edits in Photoshop
- never save or work on a file more than once (generational losses)

... then to heck with RAW.

Personally, there is very little chance of me nailing 100% of all of these things all the time, so I shoot nothing but RAW 100% of the time and don't waste a shot because of the limitations that JPG imposes and my shots all look better because of it.

To the people that say that one can shoot JPG unless they screw up their exposures definitely doesn't know much about what RAW offers, just based on that comment alone.

Specific example. Hockey. I shoot in M mode with an iso of 640 @ 1/500, F2.8 and WB 4250, which is perfect for the arena I shoot. The only processing I have to do is up the contrast because I shoot from behind that 1/4" thick plexiglass. Other then that, all I do is crop to 8x10, shrink to 300dpi and save it as a max level jpg.
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Old 05-03-2012   #114
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Default Re: Jpeg or RAW?

In the end for a pro, time is money. If they are going to produce a 300dpi image at the in camera resolution, shooting jpeg's is just cheap and efficient.

Some times the best quality is not needed, sometimes there is no time to wait for the camera to save raw files, sometimes, there are legal reasons it is better to just let the camera do it. As I said in my previous post, if you do not have a reason to shoot jpeg's, it is better to shoot raw.

Everybody, please note, that is not the same thing as saying you have to shoot raw. Some people just to not want to take the time to do something that they are entirely satisfied to let the camera do. However, anyone who prints their images in various sized, and does web images, and sends out to publishers (Yes, most publishers want jpeg's, but they want them at the size and resolution they want, so you often half to make custom images for them), then raw is the best way to go.

I notice that I mentioned custom images in that aside in the previous paragraph, in the end, that is the key point, if you want custom images you should be shooting raw. If you have no need for custom images, then just stick to jpeg's.
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Old 05-03-2012   #115
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Default Re: Jpeg or RAW?

Quote:
Originally Posted by jerryph View Post
Actually, if you can...
- accurately adjust your WB in camera with every shot
- shoot without needing noise reduction in camera
- pull all the detail info from shadows that you need in camera
- get the quality sharpening that you want in camera
- cropping your pic 100% in camera
- does absolutely no edits in Photoshop
- never save or work on a file more than once (generational losses)

... then to heck with RAW.
If you have
  • Unlimited disk space
  • CF/SD cards 5 times larger and 20x more costly
  • Poor lighting (which might not be your fault)
  • Inability to set proper exposure (which is definitely your fault)
  • A supercomputer, or plenty of free time for the extra processing of files 5x larger, with embedded recipes, and with embedding JPGs (ugh, raw formats embed JPGs? How dare they?!)
  • A T-1 network connection, or plenty of free time for uploading files 5x larger
  • Never use any software that requires an open format, like nearly all free software that depends on the netpbm libraries
  • Hyper vision that resolves color higher than normal humans can see (it's possible, and essentially a reverse-color-blindness, and extremely rare)
  • 20/10 or better vision normally so you can actually see the color issues that are usually beyond normal vision
  • A printer or color lab that takes TIFFs directly without conversion
  • Inability to crop at 8 pixel boundaries
Then to heck with JPG!


Of course, my list is tongue-in-cheek, but it should demonstrate the problems with making such absolute statements like the list advocating raws. The previous list is simply wrong for all sorts of reasons, the primary reason is that it's claiming if you cannot do the list 100% of the time, then that somehow proves the case. But there's no support to show that failure of any of those points reaults in total failure.


The obvious fallacy is clear simply by stating:
Do you do X perfectly, 100% of the time? If not, you will fail if you do Y.

Do you get perfect exposure 100% of the time? If not, don't use JPGs.
Do you focus perfectly 100% of the time. If not, don't use a camera.

This is EXACTLY the same logic.


This fallacy should demonstrate how photography is not a pure science, unlike, e.g. theoretical mathematics. The master photographer knows the tradeoffs, and will use the appropriate tools with those tradeoffs kept in check. He knows his photographic hammer also has a claw on the other side.

The padawan photographer, however, will assume the tradeoffs are absolutes because somewhere along the line that's what he learned, applied the knowledge, and got better images. However, they are still tradeoffs, and he merely never learned the advantages of using the other side of the hammer and how to apply it correctly.

I believe that advocating one tool without examining how it gets used is ignorant. It's like advocating one focal length lens with no knowledge how someone will use it. JPGs absolutely have their uses, as do raws, and one size does not fit all. Thus, this argument is kind of silly.
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Old 05-03-2012   #116
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Default Re: Jpeg or RAW?

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Originally Posted by apaflo View Post
It isn't really color information that is lost though, it's granularity in tonal range. Note that bit-depth in the RAW file has nothing at all to do with color encoding, as that is accomplished with the Bayer Color Filter Array, not with encoded bits.
That sound a lot like splitting hairs, whether a tonal black and white range behind a colour filter can be considered colour information of one colour or just a granularity in tonal range for any light which happens to be filtered with one colour.

Quote:
Originally Posted by apaflo View Post
Typically the minimum is actually a 3x3 matrix, so the number of bits used to generate a pixel is (9 * 14), or 126 bits.
Now you confuse me, that a 14-bit monochrome sensor value needs in reality 126 bits of storage, which then in practical use is nearly indistinguishable from a RGB value with 8 bits per channel. I think I need Rense to unravel that mystery for me, he's playing around with convolution matrixes and vector operations just for fun where as I'm already lost when it gets to determinants and eigenvectors.

I'm out of here, before all that technical stuff convinces my camera that digital photography is actually mathematically impossible and all my pictures delete themselves in an identity crisis.

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Old 05-03-2012   #117
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Default Re: Jpeg or RAW?

The granularity is one of the big problems, and huge enlargements or tiny important contrasting lines would show up. However most eyes would not detect it on any normal print.

CMYK prints are just separate dots of only 3 colors mixed closely together, yet they produce a reasonable color gamut for many types of print. The colors they represent fool the eye.
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Old 05-03-2012   #118
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Old 05-03-2012   #119
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Default Re: Jpeg or RAW?

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Originally Posted by apaflo View Post
A 16 bit TIFF image format has 48 bits per pixel. Even a 12 bit RAW file uses at least 108 bits per pixel (and usually more). So there is a significant data loss even when producing a 16 bit TIFF image.
The way you state this makes it sound like a RAW file has several times the information of a TIFF when the information content is almost identical. Most non-geek folks would be best off considering the TIFF as equivalent to the RAW file.

For those that want to delve deeper:

- A 16 bit TIFF file stores at each pixel the red, green, and blue color levels with 16 bits of precision (total of 48 bits per pixel)
- A 16 bit RAW files stores ONLY ONE COLOR at each pixel with 16 bits of precision (total of 16 bits per pixel). Each pixel only measures exactly one of red or green or blue.

So at first glance it seems like the TIFF has 3 times the information of the RAW file. However the TIFF file is derived from the RAW and the extra color information for each pixel comes from interpolating the missing colors from other nearby pixels (aka demosaicing). See


for more info.
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Old 05-03-2012   #120
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Default Re: Jpeg or RAW?

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Originally Posted by apaflo View Post
That is absolutely not true.
Actually it is true. Try it.

Whether exporting to a 3mb JPG straight from a RAW file or first rotating and cropping, and then exporting, I can still export a higher quality JPG file than cropping or rotating (where a minor form of cropping *always* happens) than if I rotate or crop that 3mb file.

I can do a lot more with less destruction on a RAW file than trying to do it later with that JPG... and on top of that, there is that generational loss involved again.

Said another way... I think we can agree that the RAW to JPG conversion loses about 75% of total data. You crop that RAW file by 50% then export that 3mb JPG and tell me if you can crop that JPG 50% and still make it a 3mp file of equal quality. Cannot be done.

So, yes, it does make a difference.


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