Archived posting to the Leica Users Group, 2009/05/03
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]WARNING contains geeky discussion on using Raw Convertor and DNG files. This thread may only be of interest to M8 DNG users and DNG enthusiasts. Firstly background: Adobe Camera Raw (later versions) provides two profiles for the M8, one called Adobe Standard and the other called Camera Standard. These are applied via the Calibration tab. Lightroom 2 uses the same profiles. I am not finding the 'Camera Standard' very useful. It is meant to emulate the default jpeg settings for the camera. I find the Adobe Standard to be quite restrained in its rendering of primary colours. This is not a fault but a starting point for developing. For colour I prefer to achieve something closer to the Fuji Pro slide film that I used previously. Adobe generated the profiles for each supported camera type by photographing a Color Checker card under 6500K light and 2850K light. When you open a DNG file you are offered the profile/s particular to your camera type. The selected profile then interpolates from those two renderings to give you the starting point for your DNG file. Adobe offers a free DNG Profile Editor which allows you to customise any profile. It also has a function to duplicate the original process with files from your individual camera. I used their original method as follows: Color checker, WhiBal (white balance card) colour temperature meter, 2 light sources, being bright open shade and a tungsten lamp at my helpful pro dealers, Kayell here in Brisbane. I used their meter,tungsten light and outside area to establish the light as close as possible to each ideal (6500 &2850) and made two exposures of the chart and card subjects. Using Camera Raw 5.3 I opened both DNG files. I used the default ACR settings only and saved as 16 bit PSDs in ProPhotoRGB. I made two versions from each shot, applying the Adobe Standard and my customised profile. I made final web size versions of each and have posted two samples for comparison here. <http://gallery.leica-users.org/v/gh/t_001/D65AdobeStandard.jpg.html> There are a number of complications since the 8 bit Color checker RGB numbers are not always quoted in a specific colour space, and producing a final web version requires conversion to sRGB too since web browsers are not colour mangement aware anyway. But the inyent was to change the data as little as possible during all processes and treat each file identically. Every monitor will differ as well, obviously Exposure and white balance are not actually crucial in the target files although even lighting is. However you can still see significantly different rendering in the example 2 that I have posted. Subjectively the customised one is more accurate. This whole process is about the relationships between the 24 patches. I am happy to send my custom profile (small file) to anyone that is interested and would appreciate any comments on methodology or from anyone who has also experimented here. -- Cheers Geoff 'Life's not B&W, except at both ends' http://gallery.leica-users.org/v/gh/ http://www.pbase.com/hoppyman