Posted Tue Feb 22, 2005 6:22PM
My most common rejection is now "Photo shows unacceptable compression artifacts when viewed at 100%". Now, I'm shooting with an 8MP Oly C-8080 at the highest quality JPEG mode - which is almost indistinguishable from RAW or TIFF from what I've read and seen. I've done a little noise filtering and that's it. ISO is typically 100-125 or so, exposure s/b right on. Image quality should be very high, and indeed, a lot of my pictures taken with these settings have been accepted - but a lot haven't.
Now, I can't see the compression artifacts myself. I've been dealing with digital for 5 years now (this is my 4th digital camera, and I know Photoshop pretty well.) I'm looking at 100, 200, even 400% magnification and I can't see anything out of line.
Is it possible the inspectors are seeing something else that just falls under the general "compression artifacts" label? I honestly can't see what's wrong, and if I can't find it, I can't fix it! At ISO 125 I should be getting dSLR quality, so my next option would to be to shoot RAW only, which is kind of a pain.
Here is the link to two images that I happen to like. Thanks for any help!
link to two samples
Posted Tue Feb 22, 2005 6:39PM
Look along the edges of the bars in the original version of your second example and you will be able to see them. High contrast edges are where they will be most obvious.
If you are taking images out of your camera in JPEG format you are already dealing with compressed quality. The you bring it into photoshop change and resave. The quality is going down every time you save or resave as a JPEG - even at the highest quality settings.
If you have the chance to shoot in RAW, do it. It may be slightly more work but you are at least dealing with original image data. Only save as a JPEG for iStock when you have finished all modification and correction to the file.
Posted Tue Feb 22, 2005 6:39PM
Some additional information. Camera is set to highest quality JPEG, sharpening turned down to -2, then directly imported into Photoshop, edited as required (typically just a little Neat Image), then saved at JPEG quality level 12.
In Neat Image I use less than half the conservative filtering and sharpening settings, barely visible to my eyes, just a touch.
Occasionally, I use a stand alone noise filter that forces one more JPEG save, but none of the posted pictures had this extra step.
Both pictures were taken at low shutter speeds (because of the ISO 125). Maybe there is a slight amount of motion blur which bothers the inspectors? They know something is wrong but can't quite identify what it is? I've had this happen to me on other pictures.
Posted Tue Feb 22, 2005 7:19PM
As Mark already pointed out
If you are taking images out of your camera in JPEG format you are already dealing with compressed quality. The you bring it into photoshop change and resave.
The quality is going down every time you save or resave as a JPEG - even at the highest quality settings. /end quote
You should be shooting in RAW... only convert to JPEG once all your photoshop work is done.
Posted Tue Feb 22, 2005 8:17PM
First off, they are compositionally beautiful, you obviously have a good eye. I see quite a bit of banding and compression issues. I dont know your camera so I can't say why it's there, only that it's there.
Posted Tue Feb 22, 2005 9:02PM
In your first example where the very dark top part of the arch meets the lighter part, in the shadow area you will find a lot of artifacts and noise.
Very nice composition and lighting BTW.
Posted Wed Feb 23, 2005 2:25PM
Yes, I can see the problem areas that people pointed out. Thanks everone. However but I can only see the problems at about 300% magnification on a 22" monitor. At 100% magnification I can't see these problems at all.
I guess it's a matter of degree. At that 300% magnification we are talking about a truly poster size print.
I'm happy to improve my skills but it's hard for me to judge what is acceptable and what is not. Any picture, with sufficient magnification, will show flaws.
Posted Wed Feb 23, 2005 2:28PM
The images are evaluated at 100%. Perhaps you should look at calibrating your monitor, or checking on multiple monitors to be able to see it? That can be very illuminating until you learn to "see" the compression without zooming in.
Actually, an image without compression will not "show flaws" at high magnification, it will get larger blocks of colour, but you don't get the compression pattern on them.
Posted Wed Feb 23, 2005 3:23PM
I find RAW is better, not only for the lack of compression, but I end up getting better shots (color, contrast, etc) when I am able to play with the settings later.
I think a computer does a better job of processing the information as well...
(Edited on 2005-02-23 03:29:13 by Jamesmcq24)
Posted Wed Feb 23, 2005 4:03PM
I can see significant artifacting in the first image, mainly on the edges and in the shadow areas. As already mentioned, they're very nicely composed (and exposed) images.
Before joining iStock, I strictly shot high jpeg, mainly because I felt the difference in image quality was worth the gain in storage (250+ images v. 70 on a 1gb CF card!). Now I regret not shooting everything (that's stockable) in RAW. And since you're a seasoned and regular PS user, it would be a shame not to take advantage of its RAW plug-in.
(Edited on 2005-02-23 04:12:30 by digiphotoboy)
Posted Wed Feb 23, 2005 9:24PM
Looking at the photos, it appears you have a couple of dead pixels on your sensor, or perhaps dust/grime. You can see them as pure white pixels with purple fringing in the photos in the middle of medium or dark areas.
There is a fair amount of chromatic aberation as well, between heavy shadow and bright highlights, but also in some medium shadows.
Posted Thu Feb 24, 2005 1:56AM