From: Nick Dyer <nick.dyer@itdev.co.uk>
To: Hans Verkuil <hverkuil@xs4all.nl>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-media@vger.kernel.org,
Benjamin Tissoires <benjamin.tissoires@redhat.com>,
Benson Leung <bleung@chromium.org>,
Alan Bowens <Alan.Bowens@atmel.com>,
Javier Martinez Canillas <javier@osg.samsung.com>,
Chris Healy <cphealy@gmail.com>,
Henrik Rydberg <rydberg@bitmath.org>,
Andrew Duggan <aduggan@synaptics.com>,
James Chen <james.chen@emc.com.tw>, Dudley Du <dudl@cypress.com>,
Andrew de los Reyes <adlr@chromium.org>,
sheckylin@chromium.org, Peter Hutterer <peter.hutterer@who-t.net>,
Florian Echtler <floe@butterbrot.org>,
mchehab@osg.samsung.com
Subject: Re: [PATCH v2 2/8] [media] Add signed 16-bit pixel format
Date: Fri, 27 May 2016 13:52:13 +0100 [thread overview]
Message-ID: <82b68931-0da1-bd26-87c1-1cd9e2296f71@itdev.co.uk> (raw)
In-Reply-To: <57483FD1.9080704@xs4all.nl>
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.
next prev parent reply other threads:[~2016-05-27 12:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-04 17:07 [PATCH v2 0/8] Input: atmel_mxt_ts - output raw touch diagnostic data via V4L Nick Dyer
2016-05-04 17:07 ` [PATCH v2 1/8] Input: atmel_mxt_ts - add support for T37 diagnostic data Nick Dyer
2016-05-04 17:07 ` [PATCH v2 2/8] [media] Add signed 16-bit pixel format Nick Dyer
2016-05-27 12:38 ` Hans Verkuil
2016-05-27 12:52 ` Nick Dyer [this message]
2016-05-27 13:18 ` Hans Verkuil
2016-05-27 13:31 ` Nick Dyer
2016-05-04 17:07 ` [PATCH v2 3/8] [media] v4l2-core: Add VFL_TYPE_TOUCH_SENSOR Nick Dyer
2016-05-04 17:07 ` [PATCH v2 4/8] Input: atmel_mxt_ts - output diagnostic debug via v4l2 device Nick Dyer
2016-05-27 12:54 ` Hans Verkuil
2016-06-01 16:22 ` Nick Dyer
2016-05-04 17:07 ` [PATCH v2 5/8] Input: atmel_mxt_ts - read touchscreen size Nick Dyer
2016-05-04 17:07 ` [PATCH v2 6/8] Input: atmel_mxt_ts - handle diagnostic data orientation Nick Dyer
2016-05-04 17:07 ` [PATCH v2 7/8] Input: atmel_mxt_ts - add diagnostic data support for mXT1386 Nick Dyer
2016-05-04 17:07 ` [PATCH v2 8/8] Input: atmel_mxt_ts - add support for reference data Nick Dyer
2016-05-27 12:56 ` Hans Verkuil
2016-05-13 15:17 ` [PATCH v2 0/8] Input: atmel_mxt_ts - output raw touch diagnostic data via V4L Nick Dyer
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