R.G. Loc: Scotland

When I can find the time, I intend to do an experiment to determine whether there is anything to be gained from converting a Jpeg file to some RAW format (probably tif) so that it can be edited in a RAW editor in that format, as opposed to leaving it as a Jpeg and editing it in that format. I intend to pick a shot that needs extensive editing, in particular to correct the brightness levels.

Is it already widely known whether this does or doesn't make a difference?

Before the thread goes off-course, I already know that RAW gives the better starting point for editing. What I was wondering about was those times when you will be starting with a Jpeg that needs a lot of work and there is no RAW alternative. Is it better to just persevere with the Jpeg format, or is there an advantage to be had in converting to RAW to do the required editing?

EDIT - What I'm wondering about is whether it is possible to avoid editing in the Jpeg format and therefore avoid the losses and unwanted artefacts that occur as a result of editing Jpegs.

I repeat - I already know that RAW has more information and is therefore the better starting point. To clarify, this is a question about the editing process, not the starting point.

JaiGieEse Loc: Foxworth, MS

Firsties, tiff is NOT a raw format. One could save a jpg in Photoshop as Photoshop Raw, but I'm uncertain as to how much benefit one could gain from such a conversion. I suppose being able to use more of, say, Lightroom's or ACR's adjustment tools could be of some use, but once an image is captured as a jpg, much of the data is gone. Jpg is by definition a lossy format. The camera, using either its default settings or those that you've dialed in, will deliver what it thinks is a finished image. The data is trimmed of anything the camera thinks can be discarded, and you cannot get that data back. If you truly want to make use of RAW's capabilities, then shoot that way to begin with.

mwsilvers Loc: Central New Jersey

Raw and tiff are two different formats. You can't convert jpeg or tiff files to raw. If you create jpegs in camera you have already limited the data the image contains and you can't ever recover it regardless of what format you convert to. If you shoot raw to start with you have far more options.

mwsilvers Loc: Central New Jersey

Darn. You beat me by a minute :)

OddJobber Loc: Portland, OR

Yeah, what he said. Your camera shoots in RAW format or jpeg. The jpeg or jpg file has discarded data. It can be converted to RAW format but no information will be regained.

St3v3M Loc: 35,000 feet

I am not saying it cannot be done, but it needs to be understood that converting a JPG to a TIFF format will not give you a true RAW image. The technique will allow you to use programs like Adobe Camera RAW, but it is not a true RAW image.

From http://digital-photography-school.com/raw-vs-jpeg

A Raw file is…
• at least 8 bits per color – red, green, and blue (12-bits per X,Y location), though most DSLRs record 12-bit color (36-bits per location).
• uncompressed (an 8 megapixel camera will produce a 8 MB Raw file).
• the complete (lossless) data from the camera’s sensor.
• higher in dynamic range (ability to display highlights and shadows).
• lower in contrast (flatter, washed out looking).
• not as sharp.
• not suitable for printing directly from the camera or without post processing.
• read only
• waiting to be processed by your computer.

In comparison a JPEG is…
• exactly 8-bits per color (12-bits per location).
• compressed (by looking for redundancy in the data like a ZIP file or stripping out what human can’t perceive like a MP3).
• fairly small in file size (an 8 megapixel camera will produce JPEG between 1 and 3 MB’s in size).
• lower in dynamic range.
• higher in contrast.
• sharper.
• immediately suitable for printing, sharing, or posting on the Web.
• able to be manipulated, though not without losing data each time an edit is made – even if it’s just to rotate the image (the opposite of lossless).
• processed by your camera.

R.G. Loc: Scotland

OK. I read an article that gave the impression that it was.

Would PNG be an alternative?

St3v3M Loc: 35,000 feet

You cannot 20 ounces of water into an 8 ounce glass.
- Well you can try...

R.G. Loc: Scotland

Definitely no way? Even if you converted to a bitmap image first, then RAW?

St3v3M Loc: 35,000 feet

Bitmaps are a lesser quality than JPG. It is not that I am trying to stop you, it would be fun to find a way, but in the data word JPGs are Cliff notes compared to the RAW novel. RAW data holds everything the camera see while JPGs throw out much of it to save space. You cannot get back what the camera threw out.

mwsilvers Loc: Central New Jersey

Most people convert their modified raw images to jpeg for output and distribution. A high resolution jpeg will look just as good as the modified raw file it was created from, but like one created in camera, it will no longer contain all the raw data. If you wanted to make additional modifications to the image you would go back to the original raw file to do it. If you happen to have a jpeg, with no original raw file, and it needs lots of work you should modify it directly. The results you get will be dependent on various factors and might range from quite good to dismal depending on the original image's issues and your skill and understanding of the editing process.

R.G. Loc: Scotland

Sorry, I just noticed this part of your answer.

What I'm wondering about is whether it is possible to avoid editing in the Jpeg format and therefore avoid the losses and unwanted artefacts that occur as a result of editing Jpegs.

chapjohn Loc: Tigard, Oregon

When I used PSE, I processed JPEG's in ACR. I do not know if that is your concern.

St3v3M Loc: 35,000 feet

Before this gets too technical, you can make a Copy of the JPG you are working on so you can always come back to the original untouched image.

More to your question, you are looking for a Lossless Compression Format rather than the Lossy Compression Format JPGs offer therefore what you suggest may be of benefit to you. You will not have all the data a RAW image would have stored, but you will have a format that is less destructive.

This may help http://en.wikipedia.org/wiki/Image_file_formats

mwsilvers Loc: Central New Jersey

Raw is a proprietary format of your camera maker. Each manufacturer's raw format is slightly different. Raw images are captured in camera only. Regardless of the format you start with you cannot convert to raw. Once you have created a jpeg whether in camera or from a raw image, you have eliminated most of the shooting information and can NEVER get it back. You can convert it six ways from Sunday and you will still never recover the missing data.

For instance, a raw file contains all the color information of an image. You can change a raw file back and forth between B&W and color as often as you want . If you create a B&W jpeg you no longer have the data to convert it back to color. You can take a color jpeg and desaturate it to create monochrome, but once saved, you can't go back.