EOS 10D JPEGs

[paulhodson]

Although I have been shooting JPEGs at the Large/Fine setting (yes I've just got BB and will try RAW next!), I would be interested to know the differences in quality between the other JPEG settings. Is it simply a matter of the more images per card the lower the quality or is there some other detailed reason involved in the choice of size versus compression amount?

Interested in your views - I am sure someone has had the energy to check this out!

[martcol]

Hi Paul

JPEG files are referred to as "lossy" and are compressed to reduce the file size (not the image size/dimensions so i.e. same image less (compressed) data). The lower the quality of the original JPEG the higher the compression the more "loss" your image will suffer. Higher compression increases the risk and impact of artefacts and chromatic aberration. Every time you open and resave a JPEG file it compresses a bit more and is subject to more loss. You are less likely to notice that on say, a 6x4 but it will impact at 10x8 and heavily cropped images.

You can compress TIFF files and these are not "lossy."

If you have a RAW file and overcome the initial learning curve (not too steep) relating to workflow you can make your own JPEGs, TIFFs or whatever, to your heart's content.

For me, in-camera is exactly as you say a balance between storage space, files size and intended output. I am far too trigger-happy with my 10D and shoot on the basis that the more I take the greater chance of getting a decent shot - current ratio about 1000:1! :) If I'm away from home for long, I'll start in RAW and end up using JPEG. Having said that, I think the camera's end result with JPEG is the best I've come across.

Martin

[ldivinag]

martcol wrote:
Every time you open and resave a JPEG file it compresses a bit more and is subject to more loss.
Martin


just to add to martin's tip. always save the file AS the native format of the software you are working in. for example, in photoshop, as PSD. that way you preserve as much of the original's info. keep working in PSD until you need to distribute and then, finally convert back to JPG or PNG.

it's like dubbing analog VHS tapes. you know by the 3rd copy or so, it looks like crap...

[Motorsports Photo]

ALWAYS keep your original file. You can work on the originals to your hearts content and you'll always have the same start point if you need it. This overcomes most of the negative "lossy" arguments.

-Pete

[paulhodson]

Thanks - I know the basics and probably did not explain my query well enough. It is the difference between the image size (e.g. large etc) and the compression applied (e.g. Fine etc) I was querying.

If for example you happened to get the same number of pixels in a photo (whicj in practice you don't witht he 10D) by changing one or the other factor would one method provide a better image than the other?

[CyberDyneSystems]

"Large" Does refer to resolution. It is the full 6 megapixles resolution.
If you go to a lower setting than "Large" you will in fact get a physically smaller image with fewer pixels at a lower resolution.

"Fine" refers to the level of compression applied to the given jpeg "size" Jpeg. Fine is the LEAST compression and therefore the most detailed image in the jpeg format that you can get with the 10D. (except RAW of course)

I sometimes shoot at lower resolution when I am documenting something for work purposes etc. But rarely.