uncompressed AVI strangeness (v19.e and l) [solved]

[R Reynolds]

I was experimenting with saving an image series as an uncompressed AVI and I noticed that the brightness and contrast in the avi was different than the original frames. So I cooked up a grayscale test pattern, gray scale frame.tga. I made 30 sequentially numbered copies and saved them as an uncompressed avi (gray_scale_01.avi attached). Then I did a screen grab of the video on VLC. That screen grab is shown in the lower half of the attached comparison image...obviously something has changed. This is consistent with what I've been seeing in other, more typical images.  After submitting a bug report  to Steffen, I started looking around for other programs to stitch image sequences and found VirtualDub from 2013. So I unpack its zip, fire up the program and after some time with the help files I produce an avi from the same 30 copies of my test pattern. Much to my surprise it has exactly the same problem! Not a similar problem mind you, it modifies the 21 gray levels by the identical values. Now I'm beginning to think that I'm missing something...any suggestions?

test_pattern_compare.tga gray scale frame.tga

[robcat2075]

Interesting.

Here is a screengrab of (from top to bottom)

• the gray scale -
• the gray scale exported as an AVI no compression from A:M
• the gray scale exported as an AVI no compression from QuickTime
• the gray scale exported as an H.264 mov from QuickTime
• your "gray scale 01.avi" -  displayed in A:M

GrayScale_AM_QT_H264_AVIinAM.tga

jpg version...

the first four are displayed in the Quicktime player, the fifth is in A:M

The top three and fifth are faithful to each other, the fourth has the opposite problem of what you had... the brights are less bright and the darks are less dark.

Is it possible it is your viewer that is applying some "correction". Perhaps a "contrast" boost?

If you view your uncompressed AVI in A:M does it still appear altered?  When I look at your uncompressed AVI in A:M the gray values are correct when I screen capture that and check it in Photoshop.

I was unable to view your AVI in Quicktime, however.

 

 

 

[robcat2075]

I don't use VLC much but I see it does have a contrast adjustment. Maybe that got bumped on yours?

 

[R Reynolds]

Quote

I don't use VLC much but I see it does have a contrast adjustment. Maybe that got bumped on yours?

 

Of course...It was the player not the file! After running the avi through other players the source of the problem was clear. My VLC video effects switch was not turned on, so I'll have to do some more investigating.

Thanks Robert.

Now how do I erase Issue 7027 in Mantis?

[robcat2075]

22 minutes ago, R Reynolds said:

Of course...It was the player not the file! After running the avi through other players the source of the problem was clear. My VLC video effects switch was not turned on, so I'll have to do some more investigating.

Thanks Robert.

 

Hooray for quickly solved problems!

 

Quote

Now how do I erase Issue 7027 in Mantis?

You can "Add Note" at the bottom of that issue, explaining that you've found the real problem and that the issue can be "closed"