need help with jpeg compression

[robertj298]

When you say 4 Mb, is this what you see on PSP's status bar or on Windows Explorer?

The 4 mb is what is shown in psp .

[robertj298]

What I really don't understand is I never seemed to have this problem until I had to reinstall psp 9 on a new computer running vista so I wonder if vista could be the problem...Bob

[steve.ledger]

What my point is I take a raw 11 meg photo file and export it as a 57 meg tiff file in psp and do a minor adjustment to the tiff file and save as the highest quality jpeg and I end up with an700 kb file which may be ok to post to the web but not if I want to print a large photo....Bob

You won't always end up with a 700kb JPG from a RAW. I depends a lot on what the picture contains.
None-the-less, RAW is (practically) fully uncompressed data directly from the sensor without any in-camera processing having occurred.
So think of RAW as 'expanded' if you will.
Yes JPG is lossy because it throws away data that we pretty much can't detect by eye. But if you are using 100% quality setting (effectively zero compression) then the result should look perfectly fine.
Unless you resize it (dimension/resolution being smaller than the original) then the print size won't be any different from a tiff of the same res..
I doubt very much you will see any difference in when printed either (given the correct dpi)

I never seemed to have this problem until I had to reinstall psp 9 on a new computer running vista so I wonder if vista could be the problem

It's not a problem, it's a result and no, Vista doesn't have a hand in it at all.

[robertj298]

Ok I am now certain something is wrong..Some recent portraits I took and lost with my old computer I luckily still had on my memory card. I redid these raw photos and processed in psp 9. These are the photos I'm talking about being compressed so much. Well today I was lucky enough to retrieve my data from my old hard drive. The same photos that are 700kb that I just redid are 4 or 5 megs on the old hard drive processed in psp on my old computer so something has to be wrong...Bob

[steve.ledger]

Curiosity has hold of me now, so I'm going to have to ask if you could possibly email me one of the RAW files and your resulting 700kb file please?
Use sledger [at] gmail.com thanks.

We'll try to get to the bottom of it

[handrawn]

did you change the chroma sub sampling setting? [or Exif?]

[steve.ledger]

Worth checking out..
EXIF in my PENTAX dslr RAW images are as little as 3kb, not even worth considering stripping it really (if that's what you mean't??).
However, the same 9.67 MB 3036x2020 px RAW file run through PSP's optimizer at the settings suggested by Bob gives me a file 7.46 MB with EXIF and 7.43 MB without EXIF. Change the compression factor to 25% (75% quality) the file becomes 560 KB without any change to the resolution and without any noticable artifacts.
Chroma sub-sampling isn't recommended (as commented in the optimzer wizard) yet I chose 4x4 2x2 2x2 which resulted in an image size of 4.14 MB, however it failed to display in any viewer.

As asked earlier, I'd like to see the RAW file and the 700KB file which Bob created from it. I'm certain I'll find an answer if I do

[handrawn]

you are the expert on camera/RAW Steve not me - I just threw it in in case - didn't really think Exif would make a difference, but was not sure about chroma - thought if that had been changed previously and was now back to default it might be a factor?

also of course in PSP9 you can simply save a jpeg [ and as a jpeg2000 also] rather than run it through the optimiser, would that be different?

be useful to see the file, agreed

[robertj298]

Heres what I'm working on now. The original raw file was 8.25 megs. The old jpeg file I recovered off the old hard drive was 4.68 megs after some adjustments were made. If I import the same file into psp now it shows as 2.78 megs doing nothing to it. Ive tried checking my settings in adobe lightroom and they seem ok. I had to upgrade my lightroom to 2.0 after I lost my original version so maybe the new version of lightroom is compressing the file more than the old version. I have quality set 100 on the export dialog box in lightroom. BTW Steve these are pentax files comming from my k10d...Bob

[handrawn]

you run them through lightroom first? - right......

over to Steve L then, or another lightroom user...