Re: [PATCH v2 2/8] [media] Add signed 16-bit pixel format
flat view
From: Nick Dyer <hidden>
Date: 2016-05-27 12:52:48
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linux-media, lkml
On 27/05/2016 13:38, Hans Verkuil wrote:
On 05/04/2016 07:07 PM, Nick Dyer wrote:quoted
+ <refname><constant>V4L2_PIX_FMT_YS16</constant></refname> + <refpurpose>Grey-scale image</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This is a signed grey-scale image with a depth of 16 bits per +pixel. The most significant byte is stored at higher memory addresses +(little-endian).</para>I'm not sure this should be described in terms of grey-scale, since negative values make no sense for that. How are these values supposed to be interpreted if you want to display them? -32768 == black and 32767 is white?
We have written a utility to display this data and it is able to display the values mapped to grayscale or color: https://github.com/ndyer/heatmap/blob/master/src/display.c#L44 An example of the output is here: https://www.youtube.com/watch?v=Uj4T6fUCySw The data is intrinsically signed because that's how the low level touch controller treats it. I'm happy to change it to "Signed image" if you think that would be better.