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i.MX6 PAL deinterlacer artifact

Question asked by Herve Schmitt on Nov 19, 2013
Latest reply on Dec 24, 2013 by Herve Schmitt

We use PAL camera sensors (via a TVP5154 video decoder) on i.MX6 and have installed the Freescale patch described by De-interlace Capture Device + a small capture modification to support PAL format :

 

diff --git a/drivers/mxc/ipu3/ipu_capture.c b/drivers/mxc/ipu3/ipu_capture.c

index c768d8b..578c19d 100644 (file)

--- a/drivers/mxc/ipu3/ipu_capture.c

+++ b/drivers/mxc/ipu3/ipu_capture.c

@@ -137,7 +137,7 @@ ipu_csi_init_interface(struct ipu_soc *ipu, uint16_t width, uint16_t height,

                ipu_csi_write(ipu, csi, 0x40030, CSI_CCIR_CODE_1);

                ipu_csi_write(ipu, csi, 0xFF0000, CSI_CCIR_CODE_3);

        } else if (cfg_param.clk_mode == IPU_CSI_CLK_MODE_CCIR656_INTERLACED) {

-               if (width == 720 && height == 625) {

+               if (width == 720 && (height == 625 || height == 576)) {

                        /* PAL case */

                        /*

                         * Field0BlankEnd = 0x6, Field0BlankStart = 0x2,

 

1. Dynamic aspects

It globally works as expected for dynamic aspects: with motion, we clearly see odd and even lines shifts without VDI that are significantly reduced with VDI.

 

2. Static aspects

Unfortunately, static aspects of images are slightly degraded, as shown by the following snapshots :

 

Without VDI :

WithoutVDI.PNG.png

With VDI :

WithVDI.PNG.png

 

  • We can see a blue / green line of 2 pixels thick before the last 2 lines. This is clearly the biggest artifact caused by the VDI.
  • It seems aliasing is slightly more visible with VDI (it's not really visible on the above snapshots, but we checked that on other camera).
  • Fix images with aliasing sometimes seem to move slightly when VDI is active.

 

Any idea on how to fix the blue / green line ?

 

Thanks in advance.

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