From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: jacopo mondi <jacopo@jmondi.org>
Cc: Jacopo Mondi <jacopo+renesas@jmondi.org>,
magnus.damm@gmail.com, geert@glider.be, hverkuil@xs4all.nl,
mchehab@kernel.org, festevam@gmail.com, sakari.ailus@iki.fi,
robh+dt@kernel.org, mark.rutland@arm.com, pombredanne@nexb.com,
linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org,
linux-sh@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v9 11/11] media: i2c: ov7670: Fully set mbus frame fmt
Date: Thu, 22 Feb 2018 14:47:06 +0200 [thread overview]
Message-ID: <4525290.Vz7vJ24K7t@avalon> (raw)
In-Reply-To: <20180222123600.GM7203@w540>
Hi Jacopo,
On Thursday, 22 February 2018 14:36:00 EET jacopo mondi wrote:
> On Thu, Feb 22, 2018 at 02:14:53PM +0200, Laurent Pinchart wrote:
> > On Thursday, 22 February 2018 14:04:12 EET jacopo mondi wrote:
> >> On Wed, Feb 21, 2018 at 10:28:06PM +0200, Laurent Pinchart wrote:
> >>> On Tuesday, 20 February 2018 10:58:57 EET jacopo mondi wrote:
[snip]
> >>>> This actually makes me wonder if those informations (ycbcb_enc,
> >>>> quantization and xfer_func) shouldn't actually be part of the
> >>>> supported format list... I blindly added those default fields in the
> >>>> try_fmt function, but I doubt they applies to all supported formats.
> >>>>
> >>>> Eg. the sensor supports YUYV as well as 2 RGB encodings (RGB444 and
> >>>> RGB 565) and 1 raw format (BGGR). I now have a question here:
> >>>>
> >>>> 1) ycbcr_enc transforms non-linear R'G'B' to Y'CbCr: does this
> >>>> applies to RGB and raw formats? I don't think so, and what value is
> >>>> the correct one for the ycbcr_enc field in this case? I assume
> >>>> xfer_func and quantization applies to all formats instead..
> >>>
> >>> There's no encoding for RGB formats if I understand things correctly,
> >>> so I'd set ycbcr_enc to V4L2_YCBCR_ENC_DEFAULT. The transfer function
> >>> and the quantization apply to all formats, but I'd be surprised to find
> >>> a sensor outputting limited range for RGB.
> >>
> >> Ack, we got the same understanding for RGB formats. I wonder if for
> >> those formats we wouldn't need a V4L2_YCBCR_ENC_NONE or similar...
> >
> > That, or explicitly documenting that when the format is not YUV the field
> > should be set by both drivers and applications to V4L2_YCBCR_ENC_DEFAULT
> > when written and ignored when read.
>
> Well, if no encoding is performed because the color encoding scheme is
> RGB, the colorspace does anyway define an encoding method, so it seems
> to me the latter is more appropriate (use DEFAULT and ignore when read).
>
> That's anyway just my opinion, but I could send a patch for
> documentation and see what feedback it gets.
>
> >>> Have you been able to check whether the sensor outputs limited range
> >>> of full range YUV ? If it outputs full range you can hardcode
> >>> quantization to V4L2_QUANTIZATION_FULL_RANGE for all formats.
> >>
> >> In YUYV mode, I see values > 0xf0 ( > 240, which is the max value for
> >> CbCr samples in limited quantization range), so I assume quantization
> >> is full range.
> >
> > It should be, yes. What's the minimum and maximum values you get ?
>
> From a white surface:
> min = 0x39
> max = 0xfc
>
> From a black surface:
> min = 0x00 (with 62 occurrences)
> max = 0x8b
>
> I guess that's indeed full range quantization
Could you check Y and UV separately ?
#!/usr/bin/python
import sys
def main(argv):
if len(argv) != 2:
print('Usage: %s <file>' % argv[0])
return 1
data = open(argv[1], 'rb').read()
y_min = 255
y_max = 0
uv_min = 255
uv_max = 0
for i in range(len(data) // 2):
y = data[2*i]
uv = data[2*i]
y_min = min(y_min, y)
y_max = max(y_max, y)
uv_min = min(uv_min, uv)
uv_max = max(uv_max, uv)
print('Y [%u, %u] UV [%u, %u]' % (y_min, y_max, uv_min, uv_max))
return 0
if __name__ == '__main__':
sys.exit(main(sys.argv))
> > > Actually the hardest part here was having a white enough surface to
> > > point the sensor to :)
> >
> > Pointing a flashlight to the sensor usually does the trick.
>
> I had a yellowish light that didn't work that well, I ended up putting
> a white paper sheet in front of it and then took the picture.
Time to get a white flashlight ? :-)
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2018-02-22 12:46 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-19 16:59 [PATCH v9 00/11] Renesas Capture Engine Unit (CEU) V4L2 driver Jacopo Mondi
2018-02-19 16:59 ` [PATCH v9 01/11] dt-bindings: media: Add Renesas CEU bindings Jacopo Mondi
2018-02-19 16:59 ` [PATCH v9 02/11] include: media: Add Renesas CEU driver interface Jacopo Mondi
2018-02-19 16:59 ` [PATCH v9 03/11] media: platform: Add Renesas CEU driver Jacopo Mondi
2018-02-20 3:35 ` kbuild test robot
2018-02-21 12:03 ` Hans Verkuil
2018-02-21 12:29 ` Laurent Pinchart
2018-02-21 13:02 ` Hans Verkuil
2018-02-21 16:43 ` jacopo mondi
2018-02-19 16:59 ` [PATCH v9 04/11] ARM: dts: r7s72100: Add Capture Engine Unit (CEU) Jacopo Mondi
2018-02-19 16:59 ` [PATCH v9 05/11] media: i2c: Copy ov772x soc_camera sensor driver Jacopo Mondi
2018-02-19 16:59 ` [PATCH v9 06/11] media: i2c: ov772x: Remove soc_camera dependencies Jacopo Mondi
2018-02-21 12:08 ` Hans Verkuil
2018-02-19 16:59 ` [PATCH v9 07/11] media: i2c: ov772x: Support frame interval handling Jacopo Mondi
2018-02-20 4:25 ` kbuild test robot
2018-02-20 5:22 ` kbuild test robot
2018-02-20 5:22 ` [RFC PATCH] media: i2c: ov772x: ov772x_frame_intervals[] can be static kbuild test robot
2018-02-21 12:12 ` [PATCH v9 07/11] media: i2c: ov772x: Support frame interval handling Hans Verkuil
2018-02-21 15:16 ` jacopo mondi
2018-02-21 15:23 ` Hans Verkuil
2018-02-19 16:59 ` [PATCH v9 08/11] media: i2c: Copy tw9910 soc_camera sensor driver Jacopo Mondi
2018-02-19 16:59 ` [PATCH v9 09/11] media: i2c: tw9910: Remove soc_camera dependencies Jacopo Mondi
2018-02-19 16:59 ` [PATCH v9 10/11] arch: sh: migor: Use new renesas-ceu camera driver Jacopo Mondi
2018-02-19 16:59 ` [PATCH v9 11/11] media: i2c: ov7670: Fully set mbus frame fmt Jacopo Mondi
2018-02-19 19:19 ` Laurent Pinchart
2018-02-20 8:58 ` jacopo mondi
2018-02-21 15:47 ` jacopo mondi
2018-02-21 16:28 ` Hans Verkuil
2018-02-21 20:28 ` Laurent Pinchart
2018-02-22 12:04 ` jacopo mondi
2018-02-22 12:14 ` Laurent Pinchart
2018-02-22 12:36 ` jacopo mondi
2018-02-22 12:47 ` Laurent Pinchart [this message]
2018-02-22 14:26 ` jacopo mondi
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