JPG or TIFF for retouching

[bestremera]

Need some guidance on files,

My image acquisition is through a Canon A630 that produces 'Fine' jpgs of approx. 2.4 megs. The same file, saved as a tiff, is 22megs.

My manipulations tend to be a variety of simple image adjustment layers, color retouching and conversion to b&w.

My end game is to make high quality 8X10 - 12X18 prints.

If I left the files as jpegs and worked on them would I really be able to see a quality difference between that and what a tiff file would yield?

Don't want to compromise quality but the tiff file is 10X the disk space not to mention the time to process.

Which file type is best for my workflow and final output?

Thanks, Bob

[skydog]

Everything I have read recommends working and saving your files in tiff until you achieve your finished product. Only then convert to jpg. I only do this when I know I am spending a lot of time on a photo and want to achieve the best final product. Often I blow my photos to 16x20 or 24x30 and get great results. I've also have done all my work in jpg and was still satisfied with the end product. But like I said, when I'm after the best end product, I take no chances and work in tiff and at the end convert to jpg.

[mistermonday]

Saving the file in a file format that is not compressed or has lossless compression is my preferred route (TIFF, PSD). The issue is that every time you open a jpg and change the slightest thing and resave it, it looses detail because you are recompressing data which is already compressed and that compression uses a sampling algorith . If you use a low compression factor (High jpg setting like 12) the degradation is much lower and you will need to modify the file many times before you notice the difference without zooming in at high magnification. However, on jpg 12 your files will be almost as large as a compressed TIFF with LZW lossless compression option. On some images it will be much harder to see any difference than others.
In any event it is a good idea to always archive your orig jpg out of the camera. If you edit it, edit a copy only. That way you always have a solid base to begin again if you want to re-edit, re-size, etc at a later date. As your retouching skills develop over time, and as you acquire more sophisticated versions of s/w, plugins, etc, you will want to go back and redo some images and you will be glad you had the original.
Regards, Murray

[Kraellin]

when i'm scanning from a scanner, i always save in .bmp. when scanning from a negative scanner, i always save in .tiff. this, as others have mentioned, is mostly for archiving. i rarely work in .tiff. i load the image in paintshop pro from the .tiff and then save as a .pspimage, psp's proprietary format. i then do ALL my work in .pspimage. once done, if i'm loading to the web, i save a new copy in .jpg. if i'm printing, i print directly from .pspimage after merging the layers or from a copy merged layer.

so, file size is somewhat secondary... if you have the workspace/resources to do so. i've worked on 90 meg files before in psp, but i admit it tends to get slow after a while and there's really no reason to do so unless you're printing in very large sizes. normal printing used to print at about 200 dpi. anything over that in file resolution wasnt worth doing. there was no appreciable gain in print quality. today, printers are getting better and better and i'd tend to want to save in 300 dpi for printing purposes, especially on print shop quality printers or for larger formats. normally, home printers go no larger than about 13 x 19. so, a 300 dpi resolution is fine for these. commercial printers, i'd ask how fine they can do and go with that.

so, if you're printing at 12 x 18 at 200 or 300 dpi, there's your formula, and that's going to dictate the file size. 12 times 300 = 3600. 18 times 300 = 5400. so, your image size is going to be 3600 x 5400, which is 19,440,000 bytes or approximately 19 megabytes. and that comes close to your 22 meg .tiff file. if you cut this down to 200 dpi, it would obviously be a bit smaller.

but, what you really might want to do is just run some comparison tests. save your image as a .jpg and save it as a .tiff. then simply test print both and compare the results. that's really the only thing that matters in all this and the only true way to find out for sure.

[bestremera]

Thanks everybody,

I guess I'll stay in tiff and upgrade memory as needed.
You've all been very helpful.
Bob