Jpeg files and compressions

[Bob]

Felicitation for your interresting web site and forums !

I have a simple but important question. This is about to put the best
JPEG file (for photos) on the web.

Actually I take my photos at Arttoday.com and the photos come in JPEG
file when I download it.

What is the best saving solution (with photoshop 5.5) after I have
modified the photos (for instance when I change the dimension, the
setting of the contrast/luminosity, the saturation, add a text with some
effects or add other filter effects) to have an optimal quality image
for everyone on the web with actual common computer system (common
graphical card, ...).

I know that it is not recommanded to do another optimisation (i.e.
compression) on a file who is already compressed like a JPEG file (
because we lost more and more informations and quality). This means to
do not used the "save for web" function (with optimized JPEG option).

What is the best solution:

1) save as ... (do a .psd file and save for web after);

2) save a copy and select the JPEG format.

I think the best solution is 2). Is it right ?

Can I made after or later other modifications and use again the "save a
copy" function to have again the best quality ? (because my file is
already compressed and still little in size).

And ... finally I think this is the same priciple or method (i.e. I have
to use the "save a copy" function) for the .gif file for successives
modifications and saving. Is is right ?

Please note that I use photoshop 5.5 on Windows system and I have
observed that some bad effects are not observed on my own system (on
screen when viewing on the web) comparatively at some peoples with
cheaper or oldest computer.

Could you give me some good indications.

Thank you very much

Bob

[Allen]

Hi Bob,

The simple answer is if the graphic is a photo, save it a jpg. If the graphic is text or has very few colors, save it as a gif. You can adjust the jpg slider to see the file size difference as you raise the quality. I usually use 6 as my default.

In Photoshop 5.5, use the "Save for Web" option for gif. You can also use this for JPG, but I like using "Save a copy" for jpg's in 5.5.

In either case always save a photoshop psd so you always have your work

You can check out our gif vs jpg tutorial here:
Gif vs JPG

Hope that helps.

Allen