RailPictures.Net Forums

RailPictures.Net Forums (http://www.railpictures.net/forums/index.php)
-   Digital Photo Processing Forum (http://www.railpictures.net/forums/forumdisplay.php?f=15)
-   -   Help with compression (http://www.railpictures.net/forums/showthread.php?t=16610)

Oskar 08-25-2013 04:25 PM

Help with compression
 
I have a doubt regarding edition: how do you avoid that effect on the lines such like this on the side of the cars? http://www.railpictures.net/viewphot...=448732&nseq=5

I think it has to do with JPG compression, though it looks like an oversharp issue.

Thank you very much.

EMTRailfan 08-25-2013 05:25 PM

I've never had an eye for compression unless it was very bad, but what I am seeing is a blurry photo that was maybe over sharpened to try to overcome that.

Oskar 08-25-2013 05:47 PM

Quote:

Originally Posted by EMTRailfan (Post 169507)
I've never had an eye for compression unless it was very bad, but what I am seeing is a blurry photo that was maybe over sharpened to try to overcome that.

No, no; I left "sharpness" in the editor in 0, and I would have lower it more if it was possible. I can show you the original picture with some sharpening and there is no bluriness problem.
I'm not sure what's wrong.

JRMDC 08-26-2013 02:02 AM

This is called "moire" and is caused by having a series of parallel lines a) very close to each other relative to the size of a pixel, and b) at a slight angle to the horizontal/vertical lines of the pixel alignment.

Fixes/improvements:
a) do not sharpen. If you need to sharpen, select all but the potential moire areas
b) try different resize formulas (bicubic, etc - whatever your software offers)

Oskar 08-26-2013 02:17 AM

Quote:

Originally Posted by JRMDC (Post 169522)
This is called "moire" and is caused by having a series of parallel lines a) very close to each other relative to the size of a pixel, and b) at a slight angle to the horizontal/vertical lines of the pixel alignment.

Fixes/improvements:
a) do not sharpen. If you need to sharpen, select all but the potential moire areas
b) try different resize formulas (bicubic, etc - whatever your software offers)

Thanks a lot.

I have noticed that it happens in those situations you mention, so it must be that. I have never heard of "moire" in this context, but I know what the concept means.

I didn't sharpen in this case, but the resize suggestion seems like a good idea to try.

Thanks again, I will see if I can improve this picture enough as to resubmit.

Oskar 11-02-2013 01:00 AM

Quote:

Originally Posted by JRMDC (Post 169522)
b) try different resize formulas (bicubic, etc - whatever your software offers)

I finally had some time to read and learn about "interpolation" and try different resize formulas. Well, you were right, I found a better way to do it.
I'm very grateful for your help. Better late than never.

JRMDC 11-02-2013 02:07 PM

You are welcome!


All times are GMT. The time now is 02:51 AM.

Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.