Issue with colors on HDMI output on iMX6

cancel
Showing results for 
Search instead for 
Did you mean: 

Issue with colors on HDMI output on iMX6

144 Views
jeromebolduc
Contributor III

Hi,

We have an issue with our i.MX6Q module where we are getting color problems when capturing video with a webcam using gstreamer and we render the result over HDMI.

On this snapshot, it was captured over HDMI using i.MX6Q. You can see my reddish face the orange color of the wall.image-from-imx.jpg

Here the snapshot taken on a webcam on my PC. My face is normal and wall is more accurate.image-from-pc.jpg

What do you think could explain the problem? We tried to change IPU quantization levels to fit 0-255 but it seems the IPU only works in limited mode, is that right?

We did a simple test to send a grayscale 0-255 over HDMI on the iMX6, here is the original picture:

gradient.jpg

Here is what we capture over HDMI:

monitor.jpg

We are missing the first 2x black steps and the last 2x white steps.

Is there an auto clipping? Is that would explain the reddish issue shown on the images above?

Any insight would be appreciated.

Regards,

Jérôme

0 Kudos
7 Replies

96 Views
jeromebolduc
Contributor III

Any help from NXP?

Jérôme

0 Kudos

107 Views
jeromebolduc
Contributor III

Any throughts on this? How to change SAT_MODE parameter at runtime?

Regards,
Jerome

0 Kudos

57 Views
joanxie
NXP TechSupport
NXP TechSupport
0 Kudos

123 Views
joanxie
NXP TechSupport
NXP TechSupport

did you use your customized board, right? what bsp version do you use? and if you don't connect HDMI, save the capturing picture to the file, is it the color ok?

 

0 Kudos

120 Views
jeromebolduc
Contributor III

Yes, we tried our custom board. Using Variscite VAR-SOM-MX6. Also have the same results using their latest BSP Dunfell 5.4.142 and their development kit. I suspect an issue with IPU/G2D drivers.

If we are using a gstreamer pipeline and we decode this JPEG image and encode it again and save it to a file, gray scale is preserved. It has something to do with the IPU I suppose.

We found out that the HDMI output seems to be RGB limited in the AVI infoframe over HDMI and that the content is full-scale. 

Is there a way to tell the IPU to work in 16-235?

I tried to get an access to the IC Task parameters through an utility called memtool. Do you know if there is a way to access the SAT_MODE parameter?ic-task-parameters.png

Please let me know about your findings.

Regards,

Jerome

0 Kudos

94 Views
joanxie
NXP TechSupport
NXP TechSupport

pls refer to the enclosed csc sample code which can calculate the CSC matrix and updates in real time from given parameters(Brightness,Contrast,Saturation,Hue, and gamma).

 

0 Kudos

77 Views
jeromebolduc
Contributor III

Thanks, I am more interested in answering this question:

Do you know if there is a way to access the SAT_MODE parameter?

Regards,

Jerome

0 Kudos