Another Conversion Question

[Ron Kruger]

I'm developing a system for handling my RAW/JPEG images, but a quality question came to mind:
Does a RAW image that I convert to TIFF and then take into PS and convert to JPEG have the same quality as the JPEG of the same image downloaded directly?
(This assumes, of course, that I do nothing but convert.)
Likewise, does a RAW image that I download and convert to JPEG in my camera's computer software, have the same quality as the JPEG of the same image coverted in my camera at the time of shooting?
I assumed they would all be nearly identical, but from playing around, I'm noticing different file sizes.
And can someone explain what JPEG 2000 means in PS's save features?

[drg]

Ron,

First JPEG 2000 is an updated and potentially lossless form of JPEG encoding. It is still JPEG, which means a large amount of information, i.e. picture quality, is permanently lost. It uses a different encoding method that does not continue to degrade the photo with subsequent save cycle. JPEG 2000 has not fully caught on as of this posting, probably because there are better alternatives and it still has the same type of artifacts in files that may not be desired.

Regular JPEG compression uses a cosine driven sampling transformation and JPEG2000 uses what is called wavelet technology to do the deed. See this link for JPEG2000 spec.

http://www.jpeg.org/jpeg2000/


The JPEG conversion question falls into the category of the rest of the questions I've seen from you lately. The quality is based upon the settings that are applied to render the final JPEG output. In Photoshop products there is a range of numbers, that the higher the number, the higher the quality up to 100%. That is 100% of the formula that ADOBE has implemented to sample the data and produce the JPEG format.

In a Camera, there is a tradeoff in speed to produce that file. The newest cameras with the fastest, latest, processors due a fine job, and you can even specify various processing add-ons from contrast, color adjustments, sharpening, etc.

But remember, it isn't a camera as much as a computer equipped with peripherals to make a virtual image.

Depending upon how the transform is done, and there are several algorithms to produce the JPEG output, there will be file size differences, plus all the added infor including EXIF, IPTC, and the like that may take up a fixed amount of file space, no matter what other options are selected.

If you must have JPEG straight from the camera, use the RAW+JPEG to keep all your options open.

Now, the RAW-TIFF-JPEG question. This is going to depend upon,
RAW converter type/manufactuer and version, 8-16 bit TIFF format, TIFF format type (layers/no-layers/embedds, etc.), how much information you throw away in the editing process, and then you come back to, which JPEG output method are you using. All of these factor into the 'quality' question.

Quality of the output needs to be evaluated in terms of the overall post-processing techniques to be sure that noise (dynamic or color) isn't introduced, the file isn't color shifted with an inappropriate filter or tecnique and so on and so on and . . . Get the idea?

The latest version (>4.x) of ACR (Adobe Camera RAW) have made inclusions to produce (if desired) quality identical to that which comes from the camera. This is an another set of options available. This is of course supported across the product line that use ACR (Photoshop, Lightroom, ACR/Bridge, PS Elements) as a base for its RAW conversion.

Bottom line, 'just converting' isn't a standard option, except in you localized setup. Several factors go in to this and rarely for me do the 'default' settings do all that I need.

[SmartWombat]

JPEG 2000? Depends on how many application programs support it.
Same reason I haven't adopted DNG.
As I read the link drg posted, it's not even a standard yet - but it's at the final committee draft stage.

RAW-TIFF-JPEG vs JPEG produced in the camera?
It depends. I am pretty certain it wont' look quite the same.
Depends on the in-camera software that does the conversion, compared to the RAW-TIFF conversion software and its settings, and then the TIFF to JPEG conversion software and its settings.

Some people say that you can always do a better job if you optimise the conversion yourself (from RAW to JPEG) than if you do it in camera with the RAW+JPEG option.
You have to balance custom tuning each image and the time it takes, vs the in-camera conversion, particularly with a Canon using the picture styles to tune images to "the look" that you want without having to do post-processing.

To me it's a quantity vs quality issue.
Fast or Good ?
I don't think you can have both.
But maybe you can get good enough out of the in-camera settings.