Working with JPEG files

[eugene_winter]

This is a novice question, but which of the following two editing

methods will result in a better image?

<p>1. Apply edits directly on 8-bit jpeg files, or<br>

2. Convert jpeg files to 16-bit tiff and perform edits, then convert

them back to 8-bit jpeg for printing</p>

 

Thanks.

[jimstrutz]

Your scenario doesn't allow for direct conversion of camera data, or RAW conversion to 16 bit tiff. That would be better, if possible.

 

But if you apply all your edits to the jpeg file, without any saving and then reopening, and you only resave it once at the lowest compression setting, you would probably not be able to detect any difference than going to 16 bit tiff & back.

 

If you convert to 16 bit tiff, edit and then reconvert back to jpeg at the lowest compression, you still introduce the same amount of jpeg artifacting as staying in jpeg. Converting from 8 bit to 16 bit doesn't add any new/real image information, and reverting back to 8 bit will cause you to loose any theoretical gains. So I don't see how this will help.

 

But if you are the type to fix & adjust, save & test print your image, and then reopen to fix/adjust again, you are better off converting to tiff until you are done. Also, if you think you might print at different sizes in the future, you will have to reopen the file, resize, and resharpen to suit. In situations like these you are better off keeping the file in tiff until you are forced to convert.

 

Why do you have to convert to jpeg to print?

[eugene_winter]

Thanks Jim, your comments makes sense. I'm so cheap that I've got only a 256mb CF card for my digital camera, so I've been forced to shooting in JPEG instead of RAW. My wishful thinking was that an 8-bit image when converted to a 16-bit TIFF would allow more room for editing, but I guess there's no free lunch.

[Ed_Ingold]

Converting to 16-bit for editing will reduce round-off errors when you make corrections, which improves the results to some degree. The histogram is somewhat smoother than when you edit in 8-bit mode. Otherwise, I haven't noticed any visible improvement, but theoretically there should be less noise in the shadow areas.

 

There's no advantage shooting in TIFF mode over JPEG, since both are 8-bit and TIFF files are four times as big. If you have a RAW mode, the files are about 1/2 the size of TIFF files and often have 12-bit color resolution.

[bill_tuthill]

Good advice above. Ideally you shouldn't edit JPEG, but given the

reality (most digicams produce JPEG, some cannot produce RAW) it's

required nowadays. I found that GIMP is my favorite JPEG editor,

because it can save at the same Q-values and chroma subsampling as the original, thus reducing lossiness. So I settled on #1 because it

just wastes too much space having lossy converted-TIFF cluttering up

my folders. A better solution is to shoot RAW, unless you hate image

editing, in which case why not go back to film.