colorchecker

I couldnt quite understand why building profiles with the colorchecker passport was leading to reds (especially) being a little oversaturated.
I got out my (more expensive) Gretagmackbeth SG chart and suddenly all was clear.
The colours on my SG chart are much richer, specifically the colours in the center which should share common values with the passport.
Now my SG chart is a few years old and should if anything have faded, the colour should not be richer!
I can only conclude that the nice matt finish on the passport that makes it easier to light and photograph has the side effect of not being as rich in colour as it should due to light scatter.
However the profile calcualtions must be based on the colour values from the reference chart, becasue the passport colours are weaker the profile is pushing the colours up too far.

I can still work with the passport but I will need to tweak the resulting profile with the Adobe DNG profile editor, less than ideal though maybe a better path if lighting the SG chart is problematic.

Oh well..

(Photograph shows SG chart and passport under the same lighting, the white rectangle shows the colours that are common to the charts and used to build profiles)

Im still experimenting with this camera profiling kit and have done some work on the strong reds.

My initial analysis was that some saturation was increased using the profile I built and in the case of reds was causing some clipping. All files were coverted to 16 bit and the Adobe 1998 colour space.

When I tried the conversion into the larger pro photo colour space I got a big surprise, it looks like the profile has found a lot of colour detail outside the Adobe 1998 colour space (see the diagram above, the dots represent colour in the file and the solid object is the Adobe 1998 colour space).

In the Pro Photo Colour space there is no clipping, just extended colour…

When I use the standard Adobe camera profile and convert to Pro Photo the colour just about creeps out of the Adobe 1998 colour space so it looks like the custom profile really is getting some extra range out of the camera.

In order to get the advantage of this extended range it looks like I may need to convert and retouch in the Pro Photo colour space, I can always convert to Aobe 1998 with perceptual rendering if clients request.

This could be very useful for me helping clients who do copy work, will need to experiment some more…

Very excited today to get my hands on one of the new products from x-rite called the colorchecker passport.

This allows you to build custom colour profiles for cameras. Its simple to use – just shoot a frame with the checker in and then use this to build a custom profile that can then be used in Adobe Camera Raw or Lightroom.
Initial test look good, blues are more accurate (see the blue pot above), as are other colours like the teracotta pots, though reds look a little high. (Click on the image above to see a larger version).

I have given up on camera profiles in the past as the chart I used (a previous x-rite product called the SG) had a sheen on the colour tiles that made lighting/positioning the chart very difficult. The matt surface of the new product makes placement and readings much easier.

The charts are encased in a hard plastic shell that acts as its own stand and looks to be very well made, a bit of a bargin for about £80 inc VAT.

More testing to be done but Im happy with the initial results and look forward to using it on a commercial shoot next month.

You can read more here:
http://shop.colourconfidence.com/product.php?xProd=2686″

(Ellie the cat muscled in on the shot without prompting)
Stephen