Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Warning: Undefined array key "p" in /home/forum/public_html/includes/vb5/template.php(404) : eval()'d code on line 794 Which camera settings alter the pixel data of raw files? - EOS magazine forum

Announcement

Collapse
No announcement yet.

Which camera settings alter the pixel data of raw files?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Which camera settings alter the pixel data of raw files?

    I would be interested in an article explaining which camera settings actually influence the pixel data written to a raw file, which settings if any, are completely ignored and which settings may be recorded in the raw file without altering the pixel data but are intended to potentially control post-processing software.

    As an example, does WB alter the pixel data written to the raw file? Does the colour space setting alter the pixel data?

    To avoid any misunderstanding, I am not trying to associate this with the "R v J" debate because I think recent threads have demonstrated that each definitely has specific merits and corresponding use-cases. I'm purely interested in technical information regarding raw files without comparison to jpeg files.

    #2
    Re: Which camera settings alter the pixel data of raw files?

    As far as I know nothing alters the 'pixel data' written to card other than possibly the ISO setting which influences signal amplification but an article on how raw works could well clear up a lot of misconceptions....

    My understanding is that the raw data is just the total intensity value for the light that hit each pixel. The processing of this data takes place either in camera - to produce a JPEG - or externally in DPP or your raw processor of choice. Settings like white balance, lens data, shutter speeds, aperture values, Picture styles etc. are stored in a separate section of the file to be applied as required by the algorithms used in the raw processor.

    A raw file seems to be like one of those 'deconstructed' meals so beloved of trendy chefs where all the ingredients of a recipe like Boeuf Bourgignon are present on the plate but not organised in a fashion that you would recognise as such...
    Last edited by El Sid; 18-10-2016, 12:26.
    Nigel

    You may know me from Another Place....

    The new ElSid Photogallery...

    Equipment: Far too much to list - including lots of Nikon...

    Comment


      #3
      Re: Which camera settings alter the pixel data of raw files?

      Originally posted by El Sid View Post
      A raw file seems to be like one of those 'deconstructed' meals so beloved of trendy chefs where all the ingredients of a recipe like Boeuf Bourgignon are present on the plate but not organised in a fashion that you would recognise as such...
      I had a look through the source code for dcraw a while back and my feeling is probably that the beef is still walking in the field! :-)

      Comment


        #4
        Re: Which camera settings alter the pixel data of raw files?

        My understanding is that the camera sensor pixels record incoming photons of light as captured valence electrons in a associated 'well'. The camera itself is an analogue recording mechanism. The read out voltages from the individual wells are then changed by the specific ISO setting by internal amplifiers before being sent to analogue to digital conversion and consequently RAW file recoding. There will also be some pre-processing if the sensor is a colour recording device and this will depend on the type ( Canon use a Bayer matrix) - therefore the colour seen in each RAW pixel is not the colour recorded by the sensor but one resulting from demosaicing algorithms.
        I hope that helps (somewhat).
        James


        Sent from my iPad using Tapatalk HD
        James Boardman Woodend
        www.jameswoodend.com

        Comment


          #5
          Re: Which camera settings alter the pixel data of raw files?

          whatever he said LOL

          Comment


            #6
            Re: Which camera settings alter the pixel data of raw files?

            My understanding is that the de-mosaicing algorithms are applied at the conversion stage to create the 3-channel image we know and love. Writers in the magazine frequently mention the different way that DPP and ACR create a different look.

            Yep, I think we do need an article... rolleyes.gif
            Last edited by El Sid; 18-10-2016, 17:53.
            Nigel

            You may know me from Another Place....

            The new ElSid Photogallery...

            Equipment: Far too much to list - including lots of Nikon...

            Comment


              #7
              Re: Which camera settings alter the pixel data of raw files?

              Agreed - I don't think the CR2 has been demosiac'd. Something which I find frustrating is why CR2 to TIFF appears to be an interpretation rather than a concrete translation. Logically, one might expect DPP to provide the best initial interpretation to TIFF even if other software provides better subsequent editing.

              Comment


                #8
                Re: Which camera settings alter the pixel data of raw files?

                Say-what-now.....!?!
                Garry Macdonald on Flickr
                Garry Macdonald on Facebook

                Comment


                  #9
                  Re: Which camera settings alter the pixel data of raw files?

                  Originally posted by digiman View Post
                  Say-what-now.....!?!
                  I'll take that as a vote in support of an article to demystify this ... :-)

                  Comment


                    #10
                    Re: Which camera settings alter the pixel data of raw files?

                    Thanks for the suggestion. We will take a look at this for a future issue of EOS magazine.
                    Robert
                    robert@eos-magazine.com

                    Comment


                      #11
                      Re: Which camera settings alter the pixel data of raw files?

                      Well that's clear!

                      For those of us that are interested I think some definitive information would be interesting at least.
                      Canon 5D3, 7D2, 60D, Canon 70-200L f2.8 IS II, Canon 300 f4L IS, Canon 16-35 f4 L, Canon 24-105mm f/4L IS USM, Canon 1.4 MkIII extender, Sigma AF 10-20mm f/3.5 EX DC HSM, Sigma 150-600 Contemporary, Tamron SP AF 70-300 F/4-5.6 Di VC USD, Canon EF-S 18-55mm 1:3.5-5.6 IS
                      https://www.flickr.com/photos/16830751@N03/

                      Comment


                        #12
                        Re: Which camera settings alter the pixel data of raw files?

                        Originally posted by antoeknee View Post
                        Well that's clear!

                        For those of us that are interested I think some definitive information would be interesting at least.
                        I can vote for that too


                        Sent from my iPad using Tapatalk HD
                        James Boardman Woodend
                        www.jameswoodend.com

                        Comment


                          #13
                          Re: Which camera settings alter the pixel data of raw files?

                          As a newcomer to the magazine & seriously wanting to learn more, I am getting a lot from reading areas that I was not even aware of. But, surely I cannot be the only newcomer, couldn't the magazine have a section for beginners & how to improve, I have learnt so much via the forum, but it would be good to read it in the magazine.

                          Comment


                            #14
                            Re: Which camera settings alter the pixel data of raw files?

                            Oops put this in the wrong place.

                            Comment


                              #15
                              Re: Which camera settings alter the pixel data of raw files?

                              I used to think that RAW consisted of the actual levels a pixel "saw", but it cannot be that simple. The pixels are filtered to one colour (R,G or B) and therefore there is at least one level of calculation which has to "fill in" the colour for, say, a red-filtered pixel for its green and blue values by looking at the neighbours. Then there is the dark level which has to be subtracted, to get rid of one level of noise, and then there is some (possible) additional noise filtering especially for high ISO. So there is quite a bit of calculation that seems to be done even for RAW images.

                              Comment

                              Working...
                              X