DM816x VPSS writeback distortion when capturing white

Jose Jimenez

Hi,

I'm developing a aplication that uses the writeback using the EZSDK 5_05_02_00 on a spectrum digital dm8168 EVM to capture the video displayed in a specific video output and then do some extra processing on that data. The problem I have is specifically when a displayed video has any pure white tones; when passes through the writeback it gets corrupted and the writeback output has a pink tone. Here's a JPEG file using the contents returned by the writeback:

In YUV, pinkish would mean that the U and V values are going too far positive, any ideas why this is happening? how could I fix this issue?

Thanks in advance for any help,
JJ

over 10 years ago

0 Margarita Gashova over 10 years ago

TI__Guru* 80190 points

Hello,

Could you provide me details how I can reproduce the issue on EVM?

What are you using gstreamer or OMX?

BR
Margarita

0 Margarita Gashova over 10 years ago

TI__Guru* 80190 points

Hello,

If I understand you right for the white color you shall have for Y 256, UV 128, but from the picture it seems that you have Y and U 256, V 128.

Could you confirm that this is your issue?

Keep in mind that the VFDC component format is YUYV(422).

BR
Margarita

0 Eugenia Guzman - RidgeRun over 10 years ago in reply to Margarita Gashova

Intellectual 300 points

Hi Margarita,

I am working with JJ in this issue. We ran more tests using videotestsrc patterns and we found differences in the V value. For example:

- White pattern

We are getting in the writeback:

Y=235 U=128 V=148

The right values are:

Y=235 U=128 V=128

- Black pattern

We are getting in the writeback:

Y=16 U=128 V=129

The right values are:

Y=16 U=128 V=128

So, it seems that the problem is not just with the white color.

Do you know where are set these coefficients in the M3 code?

Thanks,

Eugenia

0 Margarita Gashova over 10 years ago in reply to Eugenia Guzman - RidgeRun

TI__Guru* 80190 points

Hello Eugenia,

You could check this topic:

I should remind you that the overlay package can not be discuss in the public forum.

Margarita

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DM816x VPSS writeback distortion when capturing white