Distorted pixels?


posted on 14th of january, 2013



Don't be too happy about the title. I'm not going to tell you the exact process to get rid of it. Call it a trade secret reserved for the persistent guys? I'll tell you what they are exactly referring to - fix it yourself. (I'm soo mean?)

I recently intentionally uploaded a set of overprocessed images. Okay, it might bring my AR to 30% or some day to a negative number...but it doesn't bother me much. Common sense says I'll be able to upload only 20 images a week for the lack of time. And getting some rejections to improve isn't a bad idea. I'll write about my experiment.

WARNING: If you're a professional, please close this article from right here or you may pass out within the next paragraph. I assume no responsibilities for a drastic reduction in AR or uploads/month if you adopt the procedure stated below. It is just for creating a test file. Don't do it often, obviously.

So here's what I did (and you can do too. But don't submit this thing):
- Shoot a photo in JPEG at ISO400 in a compact camera (or 1600 if you have a DSLR).
- Shoot the photo indoors under a fluorescent lamp at night but set the white balance manually to daylight.
- Make sure you expose the photo properly though. And try to photograph a barcode, the ones you see on a jar of jam or whatever.
- Now open the JPEG in some noise removal software and run a noise removal.
Settings for Noiseninja users: [generate noise profile from photo- All values like sharpening, color correction,etc at defaults]
- Now save the file at JPEG again.
- Open it in Photoshop and do whatever white balance method you use and get it right. Save as JPEG for the third time, at highest quality of 12 to retain the details in this perfect photo.
=============================================================

Again, if you're a confused, extremely new newbie, the above method is the worst workflow in the world. DO NOT use it ever.
Okay, so we're done with creating the file we would be studying.

Now you have to open the JPEG and look at the barcode at 300% size. Notice the region where black line meets white, i.e. the edge of the bars in barcode. You'd see little grey/white squares there and some pink/green colors too probably. That is distorted pixels - the noise plus the chromatic problem. If you shoot a proper photo in RAW with ISO100 in daylight with all correct settings and open it at 300% and compare with our test file, you'd notice the difference. The pink/green color might still be there but there would be no clearly visible square/rectangular grey-white pixels.

So the next time you get a rejection stating chromatic aberration and distorted pixels - look at regions of high contrast (or where "dark meets light" in newbie vocabulary). You'll need to fix the colored patches.

Or if you get a rejection with noise and distorted pixels, look for those white-grey pixels. They are clearly there on the edges, especially if you did noise removal improperly. They are not visible at 100% but they are clear after 200% or more.

So that's all for this article. I wouldn't tell you how to get rid of distorted pixels. Research on it. But what I'd like to say is...it IS POSSIBLE to fix it all within 60sec in Photoshop. Do some research and find out how. I did find stuff on chromatic problems in the message boards. And most people would tell you to reduce image size to get rid of distorted pixels but that's not really necessary. You don't need to downsize your photos. I tested my procedure and worked perfectly. Of course I had decent photos to start with. Forget the test file. It was intended to bring out extreme distortion.

The image in the beginning of this article had distorted pixels around the edges of the tiny black-grey leaves printed on the cups.
Keep thinking. ;)
The basic thing is you can use gaussian blur of radius

Comments (12)

Posted by Robinstockphotos on November 01, 2013
Hi! are you talking about this blog? If yes, report incompatibility problem to Dreamstime support. :)
Posted by Robinstockphotos on January 15, 2013
Not really. I was getting rejection after rejection whenever I used photos from my Canon SX30. So I finally modified the workflow. Got my AR beaten up with experimental images.
But now I'm happy it's fixed.
Posted by Bradcalkins on January 15, 2013
Personally I think you are missing the forest for the trees if you are checking your images at 200% or higher :) DT has a quick intro on distorted pixels and other problems here: Contributor resources
Posted by Robinstockphotos on January 15, 2013
Agreed.
It depends on monitor. I don't use a big one so I feel comfortable viewing at 200%. An additional check is good, that's all.
But it pays.
You don't have to care much if you use DSLR though.
Posted by Sunguy on January 15, 2013
As stated in the first comment below, I have wondered if the evaluators are reviewing the images at more than 100 percent. This is why I check all my submissions at 200 percent before I upload them. There is a point if you go higher and higher in you viewing percentage that everything would be rejected as a mess of little squares, and the image itself will be lost in the shuffle.
Posted by Parkinsonsniper on January 15, 2013
interestingos articulos :))
Posted by Robinstockphotos on January 14, 2013
I was bored of writing dead serious articles. And the truth is, 90% of the new guys i know save intermediate files as JPEG. I myself used to too. When I was 13 something. It's worth mentioning.

And that kind of doctors are full in exotic India. Haha! ;)
We feel your country is exotic and you feel ours is. I've been all over India. Pity that I wasn't interested in photos then. Only in wildlife conservation activities. Missed the opportunity. But there isn't a lot of things out here. Whatever there is, is already on dreamstime. I don't even find much time now. Studies are taking almost all my time.
Well if they give me a free credit for a laugh, I'm paying you with a level 0 sale. ;)
Posted by Zenpix on January 14, 2013
ok, fair enough. i see what you are doing/saying.
i read it before i had my coffee---it just hit me as funny/strange, at the time.
kinda like the joke,
person says; hey doc it hurts when i do this. (person lifts his elbow)
Doc says: then dont do that.
no hard feelings i hope:)
Your so lucky~~you are in India~~one of the most exotic locals around. You prob can just step ouside your door and find a million things to shoot.
Posted by Robinstockphotos on January 14, 2013
It's mainly about telling newbies what distorted pixels is. There are MANY threads about this reaching to no conclusions. That's why I exaggerated the cause.
And Zenpix I owe you nothing because you're a professional from what you've mentioned in your bio.
And I told in the first paragraph professionals should close this. ;)

And surely someone using a compact camera can't run eraser over all the edges in the photo. But they can at least know if they have a problem.
Search for distorted pixels in message boards and see how many threads don't explain what it is.
Maybe it happens due to overprocessing. But it's a different story when you don't use DSLR always.
Posted by Zenpix on January 14, 2013
this is kinda a funny and annoying artical at the same time.

I dont understand the point of it....this is how you damage your pic. see how damaged it is. but im not gona tell you how to fix it??????

btw: what if u just change the pic u used as an example to b+w. or what if you select the damaged area and desaturate the bad pixles. or what is you use the eraser and run over the damaged pixles?

there is a bunch more ways you can fix it.

I just dont understand this artical?

and i want my time back for reading it and responding. you owe me $1,34.
thank you
Posted by Robinstockphotos on January 14, 2013
Look at it this way:
Dreamstime can upsample the JPEGs, right?
Now if someone wants to upsample the JPEG files then the JPEG would look a little better than it looks on your monitor at 150%. (I'm assuming they apply some sharpening, etc to upsampled files to compensate for loss of details).
In that case the distortion would become serious. And you never know what resolution monitor they are using. On a lower resolution monitor the same file would look apparently bigger. Like viewing on a 300 dpi screen and 180 dpi is very different. Safe to assume they are using something like that.

So inspect photos at 150% - better than way. But if the photos have been shot normally, then fine. This article is mainly for new people editing their photos a bit too much.
Posted by Miraclemoments on January 14, 2013
OK....my question is this though...are the editors really looking at the image at more than 100%. Where is the sense in that. If you are seeing distorted pixels at 100% you have seriously distorted pixels. Yep the correction is not that difficult.



Comments (12)

This article has been read 933 times. 1 readers have found this article useful.
Photo credits: Pratik Panda.

About me

Combining digital imaging with careful post processing to produce the images you are looking for, my steadily growing portfolio contains a wide range of images from space backgrounds to still life photography. All the images are painstakingly corrected for all types of noticeable noise and chromatic aberrations, however minor.

(Robinstockphotos)
Pune, IN

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