jvcleave
Posts: 36
Joined: Thu May 24, 2012 10:27 pm

Undocumented image_fx parameters

Sat Dec 15, 2018 7:45 pm

Playing around with the image_fx component I found that some of the filters accept parameters (beyond the known/documented ones). It would be awesome if we could get some confirmation/official usage documentation.

OMX_ImageFilterColourBalance
Number of Params: 4
Value Range: 0-255
Description: first value unknown or maybe not 0-255, 1-3 seem to be RGB.

OMX_ImageFilterColourSwap
Number of Params: 1
Value Range: 0-1
Description: Switches a mode - possibly an enum?

OMX_ImageFilterPosterise
Number of Params: 1
Value Range: 0-30
Description: somewhat the resolution of the posterization

OMX_ImageFilterColourPoint
Number of Params: 1
Value Range: 0-3
Description: changes color shift - possibly an enum?

OMX_ImageFilterSketch
OMX_ImageFilterWatercolor
Number of Params: 2
Value Range: 0-255
Description: Likely U and V

I also noticed that you can use any filter with OMX_IndexConfigCommonImageFilterParameters as opposed to OMX_IndexConfigCommonImageFilter

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 7131
Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: Undocumented image_fx parameters

Tue Dec 18, 2018 12:19 pm

All bar OMX_ImageFilterSketch are documented in the PiCamera docs - https://picamera.readthedocs.io/en/late ... ect_params

Yes OMX_ImageFilterSketchtakes a U & V value. It appears to be the same algorithm as OMX_ImageFilterWatercolor but with U&V both defaulted to 128.

I guess I ought to update the headers.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
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jvcleave
Posts: 36
Joined: Thu May 24, 2012 10:27 pm

Re: Undocumented image_fx parameters

Wed Dec 19, 2018 4:38 pm

oh nice - thanks for the link :)

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