From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-wg0-f44.google.com ([74.125.82.44]:61416 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965665Ab2EOV2H (ORCPT ); Tue, 15 May 2012 17:28:07 -0400 Received: by wgbdr13 with SMTP id dr13so39205wgb.1 for ; Tue, 15 May 2012 14:28:05 -0700 (PDT) Message-ID: <4FB2CA63.2000605@gmail.com> Date: Tue, 15 May 2012 23:28:03 +0200 From: Sylwester Nawrocki MIME-Version: 1.0 To: Sakari Ailus CC: Sylwester Nawrocki , linux-media@vger.kernel.org, m.szyprowski@samsung.com, riverful.kim@samsung.com, sw0312.kim@samsung.com, Kyungmin Park Subject: Re: [PATCH 03/23] V4L: Add an extended camera white balance control References: <1336645858-30366-1-git-send-email-s.nawrocki@samsung.com> <1336645858-30366-4-git-send-email-s.nawrocki@samsung.com> <20120514000234.GG3373@valkosipuli.retiisi.org.uk> In-Reply-To: <20120514000234.GG3373@valkosipuli.retiisi.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Sakari, On 05/14/2012 02:02 AM, Sakari Ailus wrote: > Hi Sylwester, > > Thanks for the patch. I noticed your pull req; I hope you could take into > account a few more comments. :) Thank you for your comments, I'll try to come up with a fix up patch. > On Thu, May 10, 2012 at 12:30:38PM +0200, Sylwester Nawrocki wrote: >> This patch adds V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE control which is >> an extended version of the V4L2_CID_AUTO_WHITE_BALANCE control, >> including white balance presets. The following presets are defined: >> >> - V4L2_WHITE_BALANCE_INCANDESCENT, >> - V4L2_WHITE_BALANCE_FLUORESCENT, >> - V4L2_WHITE_BALANCE_FLUORESCENT_H, >> - V4L2_WHITE_BALANCE_HORIZON, >> - V4L2_WHITE_BALANCE_DAYLIGHT, >> - V4L2_WHITE_BALANCE_FLASH, >> - V4L2_WHITE_BALANCE_CLOUDY, >> - V4L2_WHITE_BALANCE_SHADE. >> >> Signed-off-by: HeungJun Kim >> Signed-off-by: Sylwester Nawrocki >> Signed-off-by: Kyungmin Park >> Acked-by: Hans de Goede >> --- >> Documentation/DocBook/media/v4l/controls.xml | 70 ++++++++++++++++++++++++++ >> drivers/media/video/v4l2-ctrls.c | 17 +++++++ >> include/linux/videodev2.h | 14 ++++++ >> 3 files changed, 101 insertions(+) >> >> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml >> index 40e6485..85d1ca0 100644 >> --- a/Documentation/DocBook/media/v4l/controls.xml >> +++ b/Documentation/DocBook/media/v4l/controls.xml >> @@ -3022,6 +3022,76 @@ camera sensor on or off, or specify its strength. Such band-stop filters can >> be used, for example, to filter out the fluorescent light component. >> >> >> + >> + >> + V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE >> + enum v4l2_auto_n_preset_white_balance >> + Sets white balance to automatic, >> +manual or a preset. The presets determine color temperature of the light as >> +a hint to the camera for white balance adjustments resulting in most accurate >> +color representation. The following white balance presets are listed in order >> +of increasing color temperature. >> + >> + >> + >> + >> + >> + V4L2_WHITE_BALANCE_MANUAL >> + Manual white balance. >> + >> + >> + V4L2_WHITE_BALANCE_AUTO >> + Automatic white balance adjustments. >> + >> + >> + V4L2_WHITE_BALANCE_INCANDESCENT >> + White balance setting for incandescent (tungsten) lighting. >> +It generally cools down the colors and corresponds approximately to 2500...3500 K >> +color temperature range. >> + >> + >> + V4L2_WHITE_BALANCE_FLUORESCENT >> + White balance preset for fluorescent lighting. >> +It corresponds approximately to 4000...5000 K color temperature. >> + >> + >> + V4L2_WHITE_BALANCE_FLUORESCENT_H >> + With this setting the camera will compensate for >> +fluorescent H lighting. >> + > > I don't remember for quite sure if I replied to this already... what's the > diff between the above two? No, you didn't, otherwise I would certainly remember that ;) V4L2_WHITE_BALANCE_FLUORESCENT_H is for newer, daylight calibrated fluorescent lamps. So this preset will generally cool down the colours less than V4L2_WHITE_BALANCE_FLUORESCENT. I was even thinking about a separate control for V4L2_WHITE_BALANCE_FLUORESCENT, since some ISPs have several presets for fluorescent lighting. I dropped that idea finally though. > The colour temperature of the fluorescent light depends on the lamp; 2500 K > is not uncommon here in Finland. It's the spectrum that's different from > incandescents, not necessarily the colour temperature. > >> + >> + V4L2_WHITE_BALANCE_HORIZON >> + White balance setting for horizon daylight. >> +It corresponds approximately to 5000 K color temperature. >> + >> + >> + V4L2_WHITE_BALANCE_DAYLIGHT >> + White balance preset for daylight (with clear sky). >> +It corresponds approximately to 5000...6500 K color temperature. >> + >> + >> + V4L2_WHITE_BALANCE_FLASH >> + With this setting the camera will compensate for the flash >> +light. It slightly warms up the colors and corresponds roughly to 5000...5500 K >> +color temperature. > > This also depends heavily on the type of the flash. OK, I'm going to remove this one, and for V4L2_WHITE_BALANCE_FLUORESCENT as well. I would prefer to keep the remaining ones though. > I'd just remove the colour temperature from most of these since it looks > more like assumptions made in a particular system rather than something > generic. The colour temperature ranges are mostly rough estimates to give an overview of what these presets are. I compared multiple information sources when preparing those colour temperature ranges. So it's obviously not based on a single system. However since some may give false information, I'm going to remove them. Regards, Sylwester