| Message ID | 1462381638-7818-3-git-send-email-nick.dyer@itdev.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 05/04/2016 07:07 PM, Nick Dyer wrote: > This will be used for output of raw touch data. > > Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk> > --- > Documentation/DocBook/media/v4l/pixfmt-ys16.xml | 79 +++++++++++++++++++++++++ > Documentation/DocBook/media/v4l/pixfmt.xml | 1 + > drivers/media/v4l2-core/v4l2-ioctl.c | 1 + > include/uapi/linux/videodev2.h | 1 + > 4 files changed, 82 insertions(+) > create mode 100644 Documentation/DocBook/media/v4l/pixfmt-ys16.xml > > diff --git a/Documentation/DocBook/media/v4l/pixfmt-ys16.xml b/Documentation/DocBook/media/v4l/pixfmt-ys16.xml > new file mode 100644 > index 0000000..f92d65e > --- /dev/null > +++ b/Documentation/DocBook/media/v4l/pixfmt-ys16.xml > @@ -0,0 +1,79 @@ > +<refentry id="V4L2-PIX-FMT-YS16"> > + <refmeta> > + <refentrytitle>V4L2_PIX_FMT_YS16 ('YS16')</refentrytitle> > + &manvol; > + </refmeta> > + <refnamediv> > + <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? Regards, Hans > + > + <example> > + <title><constant>V4L2_PIX_FMT_YS16</constant> 4 × 4 > +pixel image</title> > + > + <formalpara> > + <title>Byte Order.</title> > + <para>Each cell is one byte. > + <informaltable frame="none"> > + <tgroup cols="9" align="center"> > + <colspec align="left" colwidth="2*" /> > + <tbody valign="top"> > + <row> > + <entry>start + 0:</entry> > + <entry>Y'<subscript>00low</subscript></entry> > + <entry>Y'<subscript>00high</subscript></entry> > + <entry>Y'<subscript>01low</subscript></entry> > + <entry>Y'<subscript>01high</subscript></entry> > + <entry>Y'<subscript>02low</subscript></entry> > + <entry>Y'<subscript>02high</subscript></entry> > + <entry>Y'<subscript>03low</subscript></entry> > + <entry>Y'<subscript>03high</subscript></entry> > + </row> > + <row> > + <entry>start + 8:</entry> > + <entry>Y'<subscript>10low</subscript></entry> > + <entry>Y'<subscript>10high</subscript></entry> > + <entry>Y'<subscript>11low</subscript></entry> > + <entry>Y'<subscript>11high</subscript></entry> > + <entry>Y'<subscript>12low</subscript></entry> > + <entry>Y'<subscript>12high</subscript></entry> > + <entry>Y'<subscript>13low</subscript></entry> > + <entry>Y'<subscript>13high</subscript></entry> > + </row> > + <row> > + <entry>start + 16:</entry> > + <entry>Y'<subscript>20low</subscript></entry> > + <entry>Y'<subscript>20high</subscript></entry> > + <entry>Y'<subscript>21low</subscript></entry> > + <entry>Y'<subscript>21high</subscript></entry> > + <entry>Y'<subscript>22low</subscript></entry> > + <entry>Y'<subscript>22high</subscript></entry> > + <entry>Y'<subscript>23low</subscript></entry> > + <entry>Y'<subscript>23high</subscript></entry> > + </row> > + <row> > + <entry>start + 24:</entry> > + <entry>Y'<subscript>30low</subscript></entry> > + <entry>Y'<subscript>30high</subscript></entry> > + <entry>Y'<subscript>31low</subscript></entry> > + <entry>Y'<subscript>31high</subscript></entry> > + <entry>Y'<subscript>32low</subscript></entry> > + <entry>Y'<subscript>32high</subscript></entry> > + <entry>Y'<subscript>33low</subscript></entry> > + <entry>Y'<subscript>33high</subscript></entry> > + </row> > + </tbody> > + </tgroup> > + </informaltable> > + </para> > + </formalpara> > + </example> > + </refsect1> > +</refentry> > diff --git a/Documentation/DocBook/media/v4l/pixfmt.xml b/Documentation/DocBook/media/v4l/pixfmt.xml > index d871245..6f7aa0e 100644 > --- a/Documentation/DocBook/media/v4l/pixfmt.xml > +++ b/Documentation/DocBook/media/v4l/pixfmt.xml > @@ -1619,6 +1619,7 @@ information.</para> > &sub-y12; > &sub-y10b; > &sub-y16; > + &sub-ys16; > &sub-y16-be; > &sub-uv8; > &sub-yuyv; > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > index 8a018c6..c7dabaa 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -1154,6 +1154,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt) > case V4L2_PIX_FMT_Y10: descr = "10-bit Greyscale"; break; > case V4L2_PIX_FMT_Y12: descr = "12-bit Greyscale"; break; > case V4L2_PIX_FMT_Y16: descr = "16-bit Greyscale"; break; > + case V4L2_PIX_FMT_YS16: descr = "16-bit Greyscale (Signed)"; break; > case V4L2_PIX_FMT_Y16_BE: descr = "16-bit Greyscale BE"; break; > case V4L2_PIX_FMT_Y10BPACK: descr = "10-bit Greyscale (Packed)"; break; > case V4L2_PIX_FMT_PAL8: descr = "8-bit Palette"; break; > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index 14cd5eb..ab577dd 100644 > --- a/include/uapi/linux/videodev2.h > +++ b/include/uapi/linux/videodev2.h > @@ -496,6 +496,7 @@ struct v4l2_pix_format { > #define V4L2_PIX_FMT_Y12 v4l2_fourcc('Y', '1', '2', ' ') /* 12 Greyscale */ > #define V4L2_PIX_FMT_Y16 v4l2_fourcc('Y', '1', '6', ' ') /* 16 Greyscale */ > #define V4L2_PIX_FMT_Y16_BE v4l2_fourcc_be('Y', '1', '6', ' ') /* 16 Greyscale BE */ > +#define V4L2_PIX_FMT_YS16 v4l2_fourcc('Y', 'S', '1', '6') /* signed 16-bit Greyscale */ > > /* Grey bit-packed formats */ > #define V4L2_PIX_FMT_Y10BPACK v4l2_fourcc('Y', '1', '0', 'B') /* 10 Greyscale bit-packed */ > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 27/05/2016 13:38, Hans Verkuil wrote: > On 05/04/2016 07:07 PM, Nick Dyer wrote: >> + <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. -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05/27/2016 02:52 PM, Nick Dyer wrote: > On 27/05/2016 13:38, Hans Verkuil wrote: >> On 05/04/2016 07:07 PM, Nick Dyer wrote: >>> + <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. A V4L2_PIX_FMT_ definition must specify the format unambiguously. So it is not enough to just say that the data is a signed 16 bit value, you need to document exactly how it should be interpreted. Looking at the code it seems that the signed values are within a certain range and are normalized to 0-max by this line: ssize_t gray = (data[i] - cfg->min) * max / (cfg->max - cfg->min); Are the min/max values defined by the hardware? Because in that case this pixel format has to be a hardware-specific define (e.g. V4L2_PIX_FMT_FOO_S16). Only if the min/max values are -32768 and 32767 can you really use YS16 (not sure yet about that name, but that's another issue). Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 27/05/2016 14:18, Hans Verkuil wrote: > On 05/27/2016 02:52 PM, Nick Dyer wrote: >> On 27/05/2016 13:38, Hans Verkuil wrote: >>> On 05/04/2016 07:07 PM, Nick Dyer wrote: >>>> + <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. > > A V4L2_PIX_FMT_ definition must specify the format unambiguously. So it is not > enough to just say that the data is a signed 16 bit value, you need to document > exactly how it should be interpreted. Looking at the code it seems that the > signed values are within a certain range and are normalized to 0-max by this line: > > ssize_t gray = (data[i] - cfg->min) * max / (cfg->max - cfg->min); > > Are the min/max values defined by the hardware? Because in that case this pixel > format has to be a hardware-specific define (e.g. V4L2_PIX_FMT_FOO_S16). > > Only if the min/max values are -32768 and 32767 can you really use YS16 (not sure > yet about that name, but that's another issue). I'm sorry, perhaps that is slightly misleading. The data being output is the raw capacitance values from the analogue front-end in the touch controller. Due to the physical characteristics, there is a small range in the middle of the possible outputs of the ADC which is interesting, and the heatmap tool allows mapping just that range to the possible colors, otherwise everything would look mid-grey. So heatmap is doing a job conceptually like adjusting the black point and white point of a greyscale image to bring out the detail. So the hardware itself doesn't have a conception of what those min/max values are - from the hardware point of view the values may range from -32768 to 32767 (in fact such values are commonly seen when one of the touchscreen lines has a fault or is not connected). -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/DocBook/media/v4l/pixfmt-ys16.xml b/Documentation/DocBook/media/v4l/pixfmt-ys16.xml new file mode 100644 index 0000000..f92d65e --- /dev/null +++ b/Documentation/DocBook/media/v4l/pixfmt-ys16.xml @@ -0,0 +1,79 @@ +<refentry id="V4L2-PIX-FMT-YS16"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_YS16 ('YS16')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <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> + + <example> + <title><constant>V4L2_PIX_FMT_YS16</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="9" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00low</subscript></entry> + <entry>Y'<subscript>00high</subscript></entry> + <entry>Y'<subscript>01low</subscript></entry> + <entry>Y'<subscript>01high</subscript></entry> + <entry>Y'<subscript>02low</subscript></entry> + <entry>Y'<subscript>02high</subscript></entry> + <entry>Y'<subscript>03low</subscript></entry> + <entry>Y'<subscript>03high</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>10low</subscript></entry> + <entry>Y'<subscript>10high</subscript></entry> + <entry>Y'<subscript>11low</subscript></entry> + <entry>Y'<subscript>11high</subscript></entry> + <entry>Y'<subscript>12low</subscript></entry> + <entry>Y'<subscript>12high</subscript></entry> + <entry>Y'<subscript>13low</subscript></entry> + <entry>Y'<subscript>13high</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Y'<subscript>20low</subscript></entry> + <entry>Y'<subscript>20high</subscript></entry> + <entry>Y'<subscript>21low</subscript></entry> + <entry>Y'<subscript>21high</subscript></entry> + <entry>Y'<subscript>22low</subscript></entry> + <entry>Y'<subscript>22high</subscript></entry> + <entry>Y'<subscript>23low</subscript></entry> + <entry>Y'<subscript>23high</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Y'<subscript>30low</subscript></entry> + <entry>Y'<subscript>30high</subscript></entry> + <entry>Y'<subscript>31low</subscript></entry> + <entry>Y'<subscript>31high</subscript></entry> + <entry>Y'<subscript>32low</subscript></entry> + <entry>Y'<subscript>32high</subscript></entry> + <entry>Y'<subscript>33low</subscript></entry> + <entry>Y'<subscript>33high</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> +</refentry> diff --git a/Documentation/DocBook/media/v4l/pixfmt.xml b/Documentation/DocBook/media/v4l/pixfmt.xml index d871245..6f7aa0e 100644 --- a/Documentation/DocBook/media/v4l/pixfmt.xml +++ b/Documentation/DocBook/media/v4l/pixfmt.xml @@ -1619,6 +1619,7 @@ information.</para> &sub-y12; &sub-y10b; &sub-y16; + &sub-ys16; &sub-y16-be; &sub-uv8; &sub-yuyv; diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c index 8a018c6..c7dabaa 100644 --- a/drivers/media/v4l2-core/v4l2-ioctl.c +++ b/drivers/media/v4l2-core/v4l2-ioctl.c @@ -1154,6 +1154,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt) case V4L2_PIX_FMT_Y10: descr = "10-bit Greyscale"; break; case V4L2_PIX_FMT_Y12: descr = "12-bit Greyscale"; break; case V4L2_PIX_FMT_Y16: descr = "16-bit Greyscale"; break; + case V4L2_PIX_FMT_YS16: descr = "16-bit Greyscale (Signed)"; break; case V4L2_PIX_FMT_Y16_BE: descr = "16-bit Greyscale BE"; break; case V4L2_PIX_FMT_Y10BPACK: descr = "10-bit Greyscale (Packed)"; break; case V4L2_PIX_FMT_PAL8: descr = "8-bit Palette"; break; diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index 14cd5eb..ab577dd 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h @@ -496,6 +496,7 @@ struct v4l2_pix_format { #define V4L2_PIX_FMT_Y12 v4l2_fourcc('Y', '1', '2', ' ') /* 12 Greyscale */ #define V4L2_PIX_FMT_Y16 v4l2_fourcc('Y', '1', '6', ' ') /* 16 Greyscale */ #define V4L2_PIX_FMT_Y16_BE v4l2_fourcc_be('Y', '1', '6', ' ') /* 16 Greyscale BE */ +#define V4L2_PIX_FMT_YS16 v4l2_fourcc('Y', 'S', '1', '6') /* signed 16-bit Greyscale */ /* Grey bit-packed formats */ #define V4L2_PIX_FMT_Y10BPACK v4l2_fourcc('Y', '1', '0', 'B') /* 10 Greyscale bit-packed */
This will be used for output of raw touch data. Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk> --- Documentation/DocBook/media/v4l/pixfmt-ys16.xml | 79 +++++++++++++++++++++++++ Documentation/DocBook/media/v4l/pixfmt.xml | 1 + drivers/media/v4l2-core/v4l2-ioctl.c | 1 + include/uapi/linux/videodev2.h | 1 + 4 files changed, 82 insertions(+) create mode 100644 Documentation/DocBook/media/v4l/pixfmt-ys16.xml