RAW vs JPEG

[Saorsa]

To an extent, it doesn't matter what you shoot in. The image will ultimately end up as a JPEG or TIFF file for display or printing. TIFFs don't present a problem since they are uncompressed.

However, each time you do something to a JPEG and save it you are creating a new file which is re compressed. Over time this can lead to what are called JPEG artifacts and some of the detail of an image is lost.

I shoot raw+JPEG fine almost all the time. The JPEG fine allows me to do some quick edits and put a mildly interesting image up on the web.

If it is an image I want to work with and perhaps exhibit, I process my raw files and save with an 'a' suffix. Any subsequent JPEG processing is always done on the 'a' version and saved with another name so that the 'a' version is not changed. Perhaps 'c' for cropped, 'm' for resized for email, 'w' saved for web, etc. I consider all of those as disposable except for the raw file and the JPEG 'a' file.

[Mike Buckley]

The image will ultimately end up as a JPEG or TIFF file for display or printing.

Is there any raw file made by any camera currently being manufactured that doesn't automatically contain a full-size JPEG in the raw file? If not, it's not a matter of an image ultimately ending up as a JPEG; instead, it's a matter of all raw files storing a JPEG image, a point that a lot of novices understandably are not aware of.

As an example, I can print directly from my Nikon raw files using Nikon proprietary software. I don't know if that's because the software converts the raw data before sending the image to the printer or if it sends the embedded JPEG to the printer.

[george013]

Is there any raw file made by any camera currently being manufactured that doesn't automatically contain a full-size JPEG in the raw file? If not, it's not a matter of an image ultimately ending up as a JPEG; instead, it's a matter of all raw files storing a JPEG image, a point that a lot of novices understandably are not aware of.

As an example, I can print directly from my Nikon raw files using Nikon proprietary software. I don't if that's because the software converts the raw data before sending the image to the printer or if it sends the embedded JPEG to the printer.

I can only speak of Nikon. The embedded JPG is one of low quality. If you're using CaptureNx, after processing the RAW-file, a high quality JPG is embedded.

George

[Manfred M]

However, each time you do something to a JPEG and save it you are creating a new file which is re compressed. Over time this can lead to what are called JPEG artifacts and some of the detail of an image is lost

While this is a common perception, it is not necessarily a correct one.

The compression occurs the first time the file is saved, thereafter (unless you change something like the amount of compression you want by degrading image quality further), there seems to be no additional data loss and yes I have tried this. Logically, this makes sense, as once you have compressed a file (given the specific compression parameters), there is no opportunity for file size gains (this is why the files are compressed, of course).

The largest benefits are in going from a 12-bit or 14-bit raw file down to an 8-bit JPEG file but once a file is down to 8-bits, the potential for additional compression savings is (virtually) non-existent.

[Mike Buckley]

I can only speak of Nikon. The embedded JPG is one of low quality. If you're using CaptureNx, after processing the RAW-file, a high quality JPG is embedded.

That depends on the camera, George. I believe the Nikon D50 was the last camera they made that did not embed a full-size JPEG in the raw file. That camera was discontinued years ago. All of my Nikon cameras (D80, D5100 and D7000) embed a full-size JPEG.

[Saorsa]

I can only speak of Nikon. The embedded JPG is one of low quality. If you're using CaptureNx, after processing the RAW-file, a high quality JPG is embedded.

George

That's definitely true of Nikon. the embedded jpeg is thumbnail quality if you shoot raw only. The reason I shoot Raw+JPEG (fine) is to have a useable image SOOC for emails and web display.

[DanK]

A few of the postings on this thread are getting a bit heated. It's almost as if we are discussing a really critical choice, like whether or not to use a protective filter.

I almost never end up disagreeing with Manfred, but I will this time. It makes no difference to me whether people are confused about whether their cameras are shooting in 14- or 16-bit depth. The arguments for and against shooting raw or JPEG are the same regardless.

All digital image processing (I am leaving out the "post" deliberately, as that implies after the camera has done some) is a process of altering and discarding data. As Manfred points out, neither our output media nor our visual systems can make use of all of the data in a modern digital image. The choice is simply how you alter and discard data, and the issue is whether that choice is consequential, not whether the final product has less data than the original.

People who shoot JPEG have made two choices. First, they have assigned a good bit of the processing to a fixed algorithm in the camera rather than controlling it themselves. Second, they have opted to make this stage of processing destructive. As far as I can tell, the only reasons to do this are convenience, speed (if you are mostly satisfied with the product), and file size (affecting burst rate as well as storage). The reasons not to do it are maintaining control and avoiding data loss.

The question is simply whether this matters. Often, it won't. Sometimes, it does, at least in my experience.

Asking whether we can tell whose images were shot as raw or JPEG is asking the wrong question, IMHO. Unless someone messes up badly, it should almost always be possible to produce a nice-looking image from a well-selected in-camera JPEG processing algorithm, particularly using a low-quality display like a computer monitor. (When I was shooting JPEG, I did mess up that badly more than once.) The question is whether the photographer could get the image to look as she or he wanted. I have lost track of the times when I simply couldn't get an image to look the way I wanted, and yet other people thought the image was very nice. Most of these were a result of the inadequacy of my processing skills or unsolvable problems with the images, not a result of shooting JPEG. However, the relevance is that shooting JPEG costs the photographer processing control. Often, it won't matter. Sometimes, it will make it harder to get what you want. At least, it does for me.

So, choose the tradeoff that work best for you. I almost never have to worry about burst rate, and I never worry about storage. I have never once filled the card in my camera before uploading the images. I find basic processing of raw images fast enough that the convenience benefit of shooting JPEG is trivial for me. So, Philip, I only shoot JPEGs for snapshots, but I am not disparaging anyone who makes a different choice.

[Saorsa]

While this is a common perception, it is not necessarily a correct one.

The compression occurs the first time the file is saved, thereafter (unless you change something like the amount of compression you want by degrading image quality further), there seems to be no additional data loss and yes I have tried this. Logically, this makes sense, as once you have compressed a file (given the specific compression parameters), there is no opportunity for file size gains (this is why the files are compressed, of course).

The largest benefits are in going from a 12-bit or 14-bit raw file down to an 8-bit JPEG file but once a file is down to 8-bits, the potential for additional compression savings is (virtually) non-existent.

I'm referring to processing which might affect image size like cropping or resizing. Once it's gone, you can't get it back. If, for example, you crop a shot, resize to 1025x768 at 72 bpi and save, the data is gone.

Cropping in particular changes the compressed data.

[george013]

That depends on the camera, George. I believe the Nikon D50 was the last camera they made that did not embed a full-size JPEG in the raw file. That camera was discontinued years ago. All of my Nikon cameras (D80, D5100 and D7000) embed a full-size JPEG.

I don't know about the D50. But the embedded JPG is a low quality JPG. If I open a RAW in Capture, change something like the WB and save the file again, the file size is growing with several MB.

A JPG is not a de facto situation. JPG is a compression method on a raster image and using a compressionfactor. And even the JPG-compression method seems not to be uniform.

George

[Mike Buckley]

That's definitely true of Nikon. the embedded jpeg is thumbnail quality if you shoot raw only.

I just now shot a raw file with the Nikon D7000 camera configured to produce only a raw file. I then extracted the embedded jpeg. (I never converted the raw file.) The extracted JPEG is exactly the same size in pixels as the raw file.

[Mike Buckley]

I don't know about the D50. But the embedded JPG is a low quality JPG. If I open a RAW in Capture, change something like the WB and save the file again, the file size is growing with several MB.

That's understandable because you have added data to the file. However, that has no bearing on the size of the jpeg that was embedded in the raw file by the camera.

[Saorsa]

I just now shot a raw file with the Nikon D7000 camera configured to produce only a raw file. I then extracted the embedded jpeg. (I never converted the raw file.) The extracted JPEG is exactly the same size in pixels as the raw file.

How did you extract the jpeg?

[george013]

I just now shot a raw file with the Nikon D7000 camera configured to produce only a raw file. I then extracted the embedded jpeg. (I never converted the raw file.) The extracted JPEG is exactly the same size in pixels as the raw file.

That's impossible.

George

[george013]

That's understandable because you have added data to the file. However, that has no bearing on the size of the jpeg that was embedded in the raw file by the camera.

The only data that was added is a small text line telling the converter what to do. It's really a higher quality JPG that's making the difference.
From this point on you can do all kind of editing. Your RAW-file will change a little bit. The rasterfile will stay the same. Just a bit longer editing list.

That's why I love Capture. If I edited the RAW, I have a good JPG in the same file.
I'm using Iview as a image browser. You can see on the thumbnails which file has been edited.

George

[Mike Buckley]

How did you extract the jpeg?

I used IDimager PhotoSupreme.

EDIT: I have asked for confirmation of my understanding of how that software works at the developer's online forum and will report back once I receive definitive information.

EDIT: Confirmation has been received. See the exact information in a message posted later in the thread.

[xpatUSA]

A JPG is not a de facto situation. JPG is a compression method on a raster image and using a compressionfactor. And even the JPG-compression method seems not to be uniform.

George

Correct, George. A JPEG can even be saved in RGB space (not Y'CbCr) - not even sure why that is available.

Then there are the various compression techniques 4:4:4, 4:2:2, 4:2:0, etc. and "quality" settings for each of those.

Not to mention whether to 'optimize Huffman' or not.

Doubters: please refer to the myriad options for JPEG in FastStone Viewer.

In fact, in these fora, just saying "JPEG" tells us absolutely nothing about the image quality or it's file size.

[george013]

Correct, George. A JPEG can even be saved in RGB space (not Y'CbCr) - not even sure why that is available.

Then there are the various compression techniques 4:4:4, 4:2:2, 4:2:0, etc. and "quality" settings for each of those.

Not to mention whether to 'optimize Huffman' or not.

Doubters: please refer to the myriad options for JPEG in FastStone Viewer.

In fact, in these fora, just saying "JPEG" tells us absolutely nothing about the image quality or it's file size.

I don't think an image can be saved in a certain colour space or whatever. A digital image doesn't have a size in mm or a colour. Both are given by the monitor, printer or whatever. I don't know much about it.

George

[Saorsa]

Images exist in multiple forms and are constantly being converted from one form to another as they are moved through a system. This happens even if no image is being displayed at all. For example, many folks think of a raw file as the data on the sensor. In fact, all manufacturers are processing as that image is moved into a memory buffer and on to a storage medium.

If we took a simple 3x3 sensor from a common manufacturer the camera maker can create it's own unique format for a data file and label it raw.

123
456
789

might be read by one manufacturer as 123456789 and by another as 147258369. The manufacturer then adds EXIF data and it's own proprietary data to the file.

The data gets changed again to be displayed on an EVF or LCD display. In fact those may well be two entirely different conversions. For example, my Nikon V2 has a 1,440,000 pixel EVF and a 921,000 pixel screen.

The image data is in whatever state it is at any one point in the processing cycle but in most instances that is unknown to the user. Most of that time, it is not one of the storage formats.

[xpatUSA]

This is weird, I post an agreement with something someone said, and up comes this garbage disagreeing with my agreement, so to speak.

I don't think an image can be saved in a certain colour space or whatever.

Well, to be more precise, I should have said "color model" but "whatever" covers that nicely

In any case you are just plain wrong. Here's WIKI:

A particular conversion to Y′C_BC_R is specified in the JFIF standard, and should be performed for the resulting JPEG file to have maximum compatibility. However, some JPEG implementations in "highest quality" mode do not apply this step and instead keep the color information in the RGB color model, where the image is stored in separate channels for red, green and blue brightness components. This results in less efficient compression, and would not likely be used when file size is especially important.

Have a look at FastStone Viewer's JPEG saving options:



Do you see RGB there? I can circle it if you like.

Can you see this image?



It was stored as a JPEG RGB, not JPEG Y'CbCr.

A digital image doesn't have a size in mm or a colour.

I never said that it did . . .

Both are given by the monitor, printer or whatever.

. . . exactly what part of "file size" in my post did you not understand ?!! (or whatever)

I don't know much about it.

George

Correct.

If your intention was to automatically disagree with everything said, just to irritate, you have succeeded.

Please do not respond to this outburst, we can all guess what form your response will take

[Mike Buckley]

I used IDimager PhotoSupreme.

EDIT: I have asked for confirmation of my understanding of how that software works at the developer's online forum and will report back once I receive definitive information.

I posted a message in the developer's forum shown below in entirety:

"I am using the File Format Conversion command in the Batcher to create a JPEG file from the Nikon raw file. No other software has touched the raw file. I am not using any command having to do with the size of the JPEG being produced. When the resulting JPEG is produced, it is exactly the same size in pixels as the RAW file produced by the camera. I have concluded that the File Format Conversion command used in this manner is only extracting the embedded JPEG, which in turn proves that the JPEG embedded by the camera is a full-size JPEG.

Is there anything about the above that I am not properly understanding? The reason I am asking is that I am currently involved in an online discussion with people who are insisting that Nikon cameras do not embed a full-size JPEG in their raw files."

The software developer's response is shown below in entirety:

"Mike, you're correct. And NEF files do include a full size good quality embedded JPG. Depending on the camera model, the embedded preview is several MB in size.

Hope that helps"