i.MX6 framebuffer colour settings

[wesleyrevens]

I have a variscite var-som-mx6 board (with an i.MX6Quad) and a buildroot based software image based on the 3.14.38 Linux kernel with Qt and eglfs/framebuffer (with no directfb or X11 support).

I have been able to get 2 different types of LVDS screens working, however, The colour temperature of one of the screens is slightly higher than the other resulting in the image looking slightly more blue / washed out.

I'd like to be able to adjust the colour characteristics to allow for differences in the behaviour of the lcd panels so that the colours appear the same on both screens.

I have tried the code mentioned here: i.MX6 CSC setting sample source code to try and adjust the color temperature however it does not appear to have any effect on the graphics output when displaying a static image using the framebuffer.

Can the CSC be configured to work with RGB graphics output of the framebuffer?

Is there any userspace sample code available that can be used to set the color characteristics?

[AntoineP]

Hi,

We have the exact same behaviour on our VAR-SOM-MX6 connected to an LVDS screen. MXCFB_CSC_UPDATE ioctl command doesn't seem to impact any change on the screen but MXCFB_SET_GAMMA do. How did you resolve this?

Thanks.

[wesleyrevens]

Thanks Igor, I have had a look at the ipu examples and the csc example converts the pixel formats

of various images images to RGB565.

I haven't been able to find any examples that set the contrast, color, etc of the IPU output

for graphics.

From the code mentioned here: i.MX6 CSC setting sample source code

It looks like I need to be using the MXCFB_CSC_UPDATE ioctl command.

However, this command did not appear to do anything to the graphics output when I tested it.

[igorpadykov]

Hi Wesley

one can look below at useful answers from our ipu experts

https://community.nxp.com/message/373663#comment-373663

iMX6Q display adjustment

Best regards

igor

[igorpadykov]

Hi Wesley

please look at csc usage in sect.7.3.15 Video conversion

attached Linux User Guide. Link below also has some csc examples

ipu-examples release notes - v0.1

Best regards

igor

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