Hi Laurent It is actually a very good comment. :) In our case we have implemented the format ourselves in the FPGA and we support both 0-255 and 0-179 Hue ranges. After some weeks of use, only the 0-179 range is used in userpace. The reasons for this is mainly that it is the format used by OpenCV http://docs.opencv.org/3.1.0/de/d25/imgproc_color_conversions.html#color_convert_rgb_hsv&gsc.tab=0 , but also because it is very efficient to convert from 0-360 to 0-180 and the lose of color resolution (256/180) does not lead to (human) perceptible differences. All that said, I would not mind to implement also the 0-255 range, but I do not know which API should be the best way to do it. quantization? it looks nice, but it is not really a quantization... a control? a bit messy.... fourcc? seems good... I am open to anything :), but I am not the right guy for making the decision. Hans, could you help me? Thanks! On Fri, Jul 15, 2016 at 8:11 PM, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > Hi Ricardo, > > Thank you for the patch. > > On Friday 15 Jul 2016 18:13:15 Ricardo Ribalda Delgado wrote: >> Describe the HSV formats >> >> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx> >> --- >> Documentation/media/uapi/v4l/hsv-formats.rst | 19 ++ >> Documentation/media/uapi/v4l/pixfmt-packed-hsv.rst | 253 ++++++++++++++++++ >> Documentation/media/uapi/v4l/pixfmt.rst | 1 + >> Documentation/media/uapi/v4l/v4l2.rst | 5 + >> 4 files changed, 278 insertions(+) >> create mode 100644 Documentation/media/uapi/v4l/hsv-formats.rst >> create mode 100644 Documentation/media/uapi/v4l/pixfmt-packed-hsv.rst >> >> diff --git a/Documentation/media/uapi/v4l/hsv-formats.rst >> b/Documentation/media/uapi/v4l/hsv-formats.rst new file mode 100644 >> index 000000000000..f0f2615eaa95 >> --- /dev/null >> +++ b/Documentation/media/uapi/v4l/hsv-formats.rst >> @@ -0,0 +1,19 @@ >> +.. -*- coding: utf-8; mode: rst -*- >> + >> +.. _hsv-formats: >> + >> +*********** >> +HSV Formats >> +*********** >> + >> +These formats store the color information of the image >> +in a geometrical representation. The colors are mapped into a >> +cylinder, where the angle is the HUE, the height is the VALUE >> +and the distance to the center is the SATURATION. This is a very >> +useful format for image segmentation algorithms. >> + >> + >> +.. toctree:: >> + :maxdepth: 1 >> + >> + pixfmt-packed-hsv >> diff --git a/Documentation/media/uapi/v4l/pixfmt-packed-hsv.rst >> b/Documentation/media/uapi/v4l/pixfmt-packed-hsv.rst new file mode 100644 >> index 000000000000..b297aa4f7ba6 >> --- /dev/null >> +++ b/Documentation/media/uapi/v4l/pixfmt-packed-hsv.rst >> @@ -0,0 +1,253 @@ >> +.. -*- coding: utf-8; mode: rst -*- >> + >> +.. _packed-hsv: >> + >> +****************** >> +Packed HSV formats >> +****************** >> + >> +*man Packed HSV formats(2)* >> + >> +Packed HSV formats >> + >> + >> +Description >> +=========== >> + >> +The HUE (h) is meassured in degrees, one LSB represents two degrees. > > Is this common ? I have a device that can handle HSV data, I need to check how > it maps the hue values to binary, but I'm pretty sure they cover the full > 0-255 range. We would then have to support the two formats. Separate 4CCs are > an option, but reporting the range separately (possibly through the colorspace > API) might be better. Any thought on that ? > >> +The SATURATION (s) and the VALUE (v) are measured in percentage of the >> +cylinder: 0 being the smallest value and 255 the maximum. >> + >> + >> +The values are packed in 24 or 32 bit formats. >> + >> + >> +.. flat-table:: Packed HSV Image Formats >> + :header-rows: 2 >> + :stub-columns: 0 >> + >> + >> + - .. row 1 >> + >> + - Identifier >> + >> + - Code >> + >> + - >> + - :cspan:`7` Byte 0 in memory >> + > > Do we really need all those blank lines ? > > [snip] > > -- > Regards, > > Laurent Pinchart > -- Ricardo Ribalda -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
