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Author Topic: feedback please  (Read 4412 times)

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« on: June 25, 2009, 19:19 »
0
Hi everyone.
First post. :) I'm new to microstock and have been uploading to some of the smaller sites to get an idea, like 123RF, Bigstock and Canstock.
I've decided to apply to iStock and two images got rejected. I'm okay with that, I know I still have a lot to learn, but I don't understand the reason and I was hoping I could get some feedback. The one that was accepted is a simple shot on a white background and these two were rejected because of 'artifacting'.

Links to full size:
http://zumawebdesign.com/photos/app_sample_view-1.jpg [nofollow]
http://zumawebdesign.com/photos/app_sample_view.jpg [nofollow]

What is artifacting and where do I see the problem? How can I prevent it? I do see some purple fringing that I should have taken care off on the tree branches, but I'm puzzled by artifacting.
Thanks so much!


« Reply #1 on: June 25, 2009, 20:19 »
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The composition is good, but the artefacts are unfortunately very very pronounced in the blue sky, canyon background, and on tree barks. The pine tree on the left has very bad red and green fringes as well.

What kind of camera did you use? Did you sharpen it? Did you turn off the in-camera sharpening? If you shot RAW, you may want to reprocess the photo from the begining.  You also need to reduce the constrast a bit. Good luck!

« Reply #2 on: June 26, 2009, 01:01 »
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I didn't know what artifacting was, either :)

If you look closely you will see a cross-hatched pattern, almost like a linen pattern. Best place to check for artifacting is in shadows or dark areas, but can appear anywhere.
Check the image at 100%. When you check for noise, always check for artifacting.

Hope that explains it a bit.

« Reply #3 on: June 26, 2009, 01:28 »
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I feel the worst problem is over sharpening.  iStock REALLY doesn't like over processed files so keep edits to a minimum, especially with things that seriously alter the entire image like sharpening and noise reduction.

One tip, if you really want to get a borderline picture online is to reduce the size of it.  This also reduces the size of any potential problems making a borderline line image acceptable.

« Reply #4 on: June 26, 2009, 04:35 »
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Artifacts?
Lets say you have an image, and you want to add some contrast to it. You will use some tool in Photoshop (Curves, for example) and you will push contrast a bit. If you overdo it (and that can happen very easily), you will get artifacts in areas of the image that contain similar lightness and color (sky, dark areas etc.)
Why this is happening? Well, let's take an example of a dark area on the image. Your camera will pick up some details from the deep shadow, but basically, whole dark area will have only slight variations in lightness. If you boost contrast, you will darken most parts of the dark area, and those slight variations in lightness will merge into one color. This way, your dark area will become one big brow (or black) blot, and it will lose details. This kind of artifacting is most common in stock photography I think. There are few more kinds of artifacts, like compression artifacts, but I doubt you made them because I guess you are processing and saving your work in high quality.

Here you have examples of artifacting in digital photography:
http://www.dpreview.com/learn/?/key=artifacts

« Reply #5 on: June 26, 2009, 14:00 »
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Thanks everyone for replying. I think I understand where artifacting is coming from, but I'm still not a 100% sure what it looks like.
Is it this sort of white line along the bark artifacting?
[nofollow]

The sharp line where the rocks meet the sky as well?
[nofollow]

I do have the original file of both of them, but unfortunately I didn't shoot RAW. I have turned off the in camera sharpening though and I'll try to reprocess as soon as I'm clear on what exactly I'm trying to avoid.

Again, thanks everyone for the help, I really appreciate it!



« Reply #6 on: June 26, 2009, 14:49 »
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The white line along the bark is a result of over sharpening.

Here is an example of artifacts in the sky from your first pic. It is kind of grainy looking. Instead, the transition between the different shades of blue should be smooth. You might need some type of noise reduction software to help with this and more importantly, shoot at the lowest ISO.
« Last Edit: June 26, 2009, 14:52 by epantha »

Squat

  • If you think you know, you know squat
« Reply #7 on: June 26, 2009, 17:09 »
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Yes, as everyone already said, you probably did over sharpen which causes the outline. but the rest of the image is soft, or over process to lose detail.
Are you using in camera noise reduction ? If so, it could do with less . As for the artifacts in the sky, you can correct that by using layers to blur for that portion.
There is an overall lack of definition, which might be due to your camera or/and lense. Hard to tell . Are you shooting at wide open aperture? Is that a zoom you are using? If yes, try to experiment with find the critical aperture (sweet spot) by stopping down until you get the sharpest part of the lense. Also, if your camera is noise reducing, try not to do that, and use a software to do all this post processing.
hope this helps. There's too little information to be truly able to say what the problem is.
Can you furnish us with more info. Camera, MP, lense, fstop used, focal lengths, sharpen+ , noise reduction +,etc.
Whatever, as already said, try shooting only in RAW then use a software for post processing. You'll have more control and better results.

« Reply #8 on: June 26, 2009, 18:43 »
0
Artifacts?
Lets say you have an image, and you want to add some contrast to it. You will use some tool in Photoshop (Curves, for example) and you will push contrast a bit. If you overdo it (and that can happen very easily), you will get artifacts in areas of the image that contain similar lightness and color (sky, dark areas etc.)
Why this is happening? Well, let's take an example of a dark area on the image. Your camera will pick up some details from the deep shadow, but basically, whole dark area will have only slight variations in lightness. If you boost contrast, you will darken most parts of the dark area, and those slight variations in lightness will merge into one color. This way, your dark area will become one big brow (or black) blot, and it will lose details. This kind of artifacting is most common in stock photography I think. There are few more kinds of artifacts, like compression artifacts, but I doubt you made them because I guess you are processing and saving your work in high quality.

Here you have examples of artifacting in digital photography:
http://www.dpreview.com/learn/?/key=artifacts


Really thorough explanation Whitechild. 

I find I can get away with some pretty intense processing if I do it in RAW.  It's real easy to get the artifacts if you are working on jpeg images.

« Reply #9 on: June 26, 2009, 18:52 »
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Thanks so much everyone. I have a Canon XSi and these were taken with the Canon 10-22 in large jpeg mode. In camera noise reduction is turned off, highlight tone is disabled, auto lighting optimizer disabled, but for picture style I had sharpness on 3, contrast +2, saturation +1 and colour tone +1. I've since disabled the sharpening too and will try to shoot RAW from now on. I'm using a Lightroom trial at the moment, but it seems to have a lot of problems with importing the XSi RAW, so I haven't been using it enough.

Thanks epantha for the crop, that helps a lot!  
I will try to reprocess and watch my settings a bit closer from now on. And I think I have to move my computer to a darker place in the house I have a heck of a time making it out, but I see what you mean. Thank you!

« Reply #10 on: June 26, 2009, 21:03 »
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Heres an example of the linen pattern I was talking about.  To me, artifacting looks like a cross hatching pattern.  I tried to take a cut big enough to see easily.

Gebbie

« Reply #11 on: June 27, 2009, 01:02 »
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I think I got it. Here's the reprocessed file:

http://zumawebdesign.com/photos/stock4-1.jpg [nofollow]

How do you guys feel about that one? Looks much smoother to me.
Is there a point resubmitting this to iStock when I apply again to show I can learn, or should I not bother and submit new images?

I'm so glad I found this forum, you guys have been incredibly helpful!

« Reply #12 on: June 27, 2009, 05:08 »
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Yes, it is smoother. I don't know if it's good idea to submit the same image... I know a guy who did it and he passed the test successfully. But everyone will tell you it's not very good idea, and you should submit new images. I personally think you should make at least one shot with some other subject. If I understood you right you already have accepted one isolated shot, so you need only 2 more images. Let one be landscape, and another one something else. They like variety in images. I would also suggest you resizing images close to 4 Mpix. I can really help you to get rid of some minor flaws...I think everyone has good experience with this. Btw, don't use sharpening if you resize your images. It could make ugly haloing around edges.

Squat

  • If you think you know, you know squat
« Reply #13 on: June 27, 2009, 07:48 »
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generally, it's best not to do any sharpening, NR,etc.. in camera. reason because the processing is irreversible. i always prefer to shoot RAW and use photoshop to do all adjusting. also shoot at the highest resolution. and if it needs sharpening, do it in RAW. many times you don't even need sharpening, just downsizing alone can produce good results without any further sharpening.
ideally you should shoot at the sharpest aperture. you can find this in lense reviews , google it . many reviews will tell you which aperture perform the best .
then instead of doing general sharpening on one image, i prefer to use layers so the sharpening is specific in a certain area . layers are the best way to go, as you can use this to correct specific problems, one at the time. all without ruining the entire image.
hope this helps.

« Reply #14 on: June 27, 2009, 10:20 »
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I agree with Tan.  No reason to do any sharpening if you take a sharp picture to start with.  And if you have to sharpen, use layers and do it selectively. 

« Reply #15 on: June 27, 2009, 11:55 »
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The sky is better, less grainy. I can still see CA on the left along the edge of the dark sandstone. The edges of the sandstone silhouettes are still over sharpened. The middle ground looked over-filtered through too much noise reduction, especially around the white tree branch (or rock ) on the right. I doubt if it will pass if you submit the full size. However, you can try to reduce the size as Whatalife suggests.

Your camera is not the problem. I know some IS diamond contributors are using the same camera or even earlier versions of the Rebel series.

« Reply #16 on: June 27, 2009, 12:20 »
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Oh I never said the camera is at fault, it's definitely the person using it. I just posted the camera info because someone asked. As I said I didn't shoot RAW and I had in camera sharpening turned on and the original file isn't all that fantastic. I've learned the lesson though. I'll do things differently from now as I understand a lot more about artifacting and the benefits of shooting RAW, no sharpening etc.
I will send new images at my next try.

« Reply #17 on: July 02, 2009, 00:16 »
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Now that you know about artifacting you can work on your photography technique. 
The tree at the Grand Canyon:  Landscapes are best shot during the "Magic Hours" that is the time just before and just after sunrise and sunset.  The tree looks to have been shot closer to mid day.  Don't cut the top of the tree off next time.

John Ford Point at Monument Valley:  You have captured very nice clouds but they would stand out better in the evening.  Try to clone out the top of the RV on the right.  Next time either move the horizon down a little more, this will show more of the sky, or move the horizon way up and have something, a cow skull or a canteen with water coming out of it, big in the forground.

Mike Norton

« Reply #18 on: July 05, 2009, 21:02 »
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I was away for a few days and just got back and re-applied for iStock. I made sure to have technically as near perferct as I can with varied subjects and I got accepted! Yay! It took them all of 5 hours from application to the 'you've been successful' email. Thanks so much everyone for your help, I've learned a lot in a couple of short weeks already and I can't wait to learn more as time goes on.

« Reply #19 on: August 10, 2009, 19:53 »
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This was a great discussion. I'm new here and learned a whole lot about the artifacting and the sharpening process when submitting. Thanks to you all. And congrats on your acceptances1


 

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