Issue with colors on HDMI output on iMX6

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Issue with colors on HDMI output on iMX6

1,518 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

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12 Replies

1,069 Views
jeromebolduc
Contributor III

Any update on how to change this parameter? My response seems to be deleted each time I post it?!

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1,082 Views
jeromebolduc
Contributor III

I would like to know how we can change live the quantization level (full and limited range) on the HDMI output. Is that possible?

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1,083 Views
jeromebolduc
Contributor III

Any update on this?

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1,093 Views
jeromebolduc
Contributor III

Do you know how to access SAT_MODE parameter through userspace?

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1,470 Views
jeromebolduc
Contributor III

Any help from NXP?

Jérôme

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1,481 Views
jeromebolduc
Contributor III

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

Regards,
Jerome

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1,431 Views
joanxie
NXP TechSupport
NXP TechSupport
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1,497 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?

 

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1,494 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

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1,468 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).

 

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1,451 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

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1,066 Views
jeromebolduc
Contributor III
Any update on this?
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