Hello again, I forgot to give you reference about the range of color temperature to handle white balance as preset. Here is the wikipedia reference, I wish I could find better one but by now it seems to be no problem. http://en.wikipedia.org/wiki/Color_temperature#Categorizing_different_lighting Cheers, Nate On Sat, Apr 11, 2009 at 5:44 AM, Dongsoo, Nathaniel Kim <dongsoo.kim@xxxxxxxxx> wrote: > On Sat, Apr 11, 2009 at 2:39 AM, Theodore Kilgore > <kilgota@xxxxxxxxxxxxxxxxxxxxxx> wrote: >> >> >> On Fri, 10 Apr 2009, Dongsoo, Nathaniel Kim wrote: >> >>> Hello everyone, >>> >>> I'm posting this RFC one more time because it seems to everyone has >>> been forgot this, and I'll be appreciated if any of you who is reading >>> this mailing list give me comment. >> >> I don't know much about the topic, and I wish I did. >> >>> I've got a big question popping up handling white balance with >>> V4L2_CID_WHITE_BALANCE_TEMPERATURE CID. >>> >>> Because in digital camera we generally control over user interface >>> with pre-defined white balance name. I mean, user controls white >>> balance with presets not with kelvin number. >>> I'm very certain that TEMPERATURE CID is needed in many of video >>> capture devices, but also 100% sure that white balance preset control >>> is also necessary for digital cameras. >>> How can we control white balance through preset name with existing V4L2 >>> API? >> >> Let's broaden the question to include digital still cameras, which present >> similar problems. They present data related to this kind of thing, that is >> obvious. But are there any standard meanings to what is there? Do you know >> anything about that? Can you help? >> > > Exactly right, but we need to see this on the top of the user space first. > Because there could be several types of camera devices could be handled. > I mean, the device that I'm intending to handle is based on I2C device > and the "digital still camera" you issued is totally based on USB > communication. > That could be different in driver implementation point of view, but > user in user space should be using in same manner. > And I think I can help to coordinate how to handle them in user space > with V4L2 API, but not so much with usb communication with digital > still cameras.(but I really want to help indeed) > Actually my expertise is totally based on mobile camera devices like > camera phone. Even though they are "mobile" camera modules, they are > very close to regular digital camera in performance and quality level > now days. > >> Two examples: >> >> The SQ905 and SQ905C cameras in stillcam mode use an allocation table, which >> presents on each line some data about the given image. In this line, byte 0 >> is a one-byte code for pixel dimensions and compression setting. Then some >> more bytes give the starting and ending locations of the photo in the >> camera's memory (actually irrelevant and superfluous information, because >> you can only ask for the photos in sequence, and with a command which has >> nothing to do with its memory location at all). Then some more bytes >> obviously have something to do with contrast, brightness, white balance, >> color balance, and so on. But I have no more idea than the Man in the Moon >> how those bytes are supposed to be interpreted. The SQ905 gives no such >> equivalent information while in streaming mode, and so there is nothing at >> all which could be done with the nonexistent information. But the SQ905C >> does obviously give such information, in a few bytes in the header of each >> frame. > > As far as I know, SQ905 (is that actually cheez camera?) is a regular > digital camera not a mobile camera module, so in that case it could be > handled in gspca and totally control through usb_control_msg. > And with my experience, I think I can help you if I have any kind of > datasheet or user manual for that. > But even if I don't have datasheet and don't know which message field > means what I'm intending to do, I think it could be possible to make > it compatible with the parameters I'm trying to make in v4l2 control. > >> >> The MR97310A cameras give similar information in the header of the photo >> itself (and in this case the camera does the same thing in webcam mode, >> too). Again, I have no idea either what these mysterious bytes are supposed >> to mean, and how to use them constructively. >> >> I could mention several other examples, too, but these will do for a start. > > OK I've got what you mean. Can I have any information like user manual > or datasheet for those SQ and MR devices? > If we make a white balance preset api in v4l2, then we should have to > implement that functionality in every single camera drivers in v4l2 if > those devices are supporting for white balance presets. > > I want to make this clear that if we have white balance preset api in > v4l2, then we can handle every camera device's white balance more user > friendly. > > Thank you for your opinion by the way. > > Nate > >> >> Are there any agreed-upon standards about this kind of thing, in the camera >> industry? Is there any source of information about it? >> >> Theodore Kilgore >> > > > > -- > ======================================================== > DongSoo, Nathaniel Kim > Engineer > Mobile S/W Platform Lab. > Digital Media & Communications R&D Centre > Samsung Electronics CO., LTD. > e-mail : dongsoo.kim@xxxxxxxxx > dongsoo45.kim@xxxxxxxxxxx > ======================================================== > -- ======================================================== DongSoo, Nathaniel Kim Engineer Mobile S/W Platform Lab. Digital Media & Communications R&D Centre Samsung Electronics CO., LTD. e-mail : dongsoo.kim@xxxxxxxxx dongsoo45.kim@xxxxxxxxxxx ======================================================== -- 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
