Pages: [1]   Go Down

Author Topic: Color Checker Passport question  (Read 3446 times)

larkis

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 330
    • My photography blog
Color Checker Passport question
« on: December 24, 2011, 01:53:10 pm »

I purchased one of those colour checker passports and the one thing that is not clear is what to profile when the illumination of a landscape scene consists of both shadows and direct light from the sun ? For example in the morning, warm sun will illuminate the surroundings but the shadows tend to be blue. Should I take a picture of the checker being hit by warm sunlight or should I keep it in the bluish shadows ? It seems that if i shoot it in the shadows (at least on my first test scene) and build a profile I get a bit to much green cast in my images, while the ones I shot with the sun hitting the target gives a pleasant look. What is the proper workflow in this situation ?

Also, when one makes profiles for various shoots and lighting conditions can the old ones be deleted ? I don't want to end up with a list of 500 profiles down the road.

Steve Weldon

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1479
    • Bangkok Images
Re: Color Checker Passport question
« Reply #1 on: December 24, 2011, 02:14:57 pm »

There is no workflow which will balance all your light sources other than to make a measurement for each light source, process the image each time for each light source, and then carefully blend with layers.   But why.. it wouldn't look natural.  Your eyes will see the scene in much the same way the camera will.  You'll see the colors as presented with the available light sources.  Get either one of those right and the others will fall into place as your eyes saw them.  Or in other words, one light source references off the other.

With a landscape you'd think of composition to determine which area you wish to favor with the most accurate light temp.  In most cases this would be the mid-tones.. the strong part of the scene with the most light.  This is where you'd take your measurement.   But if your composition is favoring shadows then go there.  Try taking a few and see how they look after processing.  This is where your creativity comes in.  With light temp/white balance there is no 'right' answer.  I use the color checker for getting close but I often vary it from there to suit by tastes.

I did a short tutorial here with the color checker you might find useful..
Logged
----------------------------------------------
http://www.BangkokImages.com

larkis

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 330
    • My photography blog
Re: Color Checker Passport question
« Reply #2 on: December 24, 2011, 02:24:05 pm »

Thanks for the answer, so is there a way to embed the dng profile i made into the file itself ? When i load the raw's from my camera into Lightroom i get Adobe Standard and Embedded in the list (this is a pentax 645D). I'm assuming the embedded profile is something the camera writes into the file, can that be replaced with my custom one so I can then throw it out from the profile list and the custom profile I made turns into the Embedded one ?

Adobe says this about the profiles:
"What's the difference between an embedded profile and an external profile?

An embedded profile is a camera profile that has been embedded in a DNG file (i.e., the profile data is stored in the DNG along with the image data). An external profile is a camera profile whose data is stored in a separate file on disk; this file has a .dcp extension. Otherwise there is no difference between embedded and external profiles."

So i guess to clarify, how can I turn the external profiles into embedded ones so I don't have to deal with a bunch of those external files a few months from now ?
« Last Edit: December 24, 2011, 02:36:58 pm by larkis »
Logged

Ellis Vener

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2151
    • http://www.ellisvener.com
Re: Color Checker Passport question
« Reply #3 on: December 25, 2011, 07:30:30 am »

It seems that if i shoot it in the shadows (at least on my first test scene) and build a profile I get a bit to much green cast in my images, while the ones I shot with the sun hitting the target gives a pleasant look. What is the proper workflow in this situation ?

Let your eye and mind guide you towards what looks right to you. No machine or externally applied automated process takes the place of your judgement.

Also, when one makes profiles for various shoots and lighting conditions can the old ones be deleted ? I don't want to end up with a list of 500 profiles down the road.

You really don't have to do one for multiple shoots  - unless perhaps you are photographing commercial products where color matching through out the process is critical.  Creating a dual illuminant profile for your specific individual camera bodies should work well 99% of the time. If you are worried about lens to lens color rendering variability you might consider creating dual illuminant profiles for each camera and lens combination.

You create a dual illuminant profile by shooting two frames of the target , one in "daylight" (around 5500˚K - electronic flash works well if you do no have access to a clear sky) and illuminate the target for the second frame with either a 2700˚K ( undimmed household tungsten bulb) or 3200˚K ( undimmed quartz-Halogen) light source.

It seems to me that one of the things you are confusing here is profiling the camera's color rendering ability with the Color Checker Passport and software, and white (actually gray) balancing for specific lighting situations.
Logged

Steve Weldon

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1479
    • Bangkok Images
Re: Color Checker Passport question
« Reply #4 on: December 25, 2011, 10:59:42 am »

Thanks for the answer, so is there a way to embed the dng profile i made into the file itself ? When i load the raw's from my camera into Lightroom i get Adobe Standard and Embedded in the list (this is a pentax 645D). I'm assuming the embedded profile is something the camera writes into the file, can that be replaced with my custom one so I can then throw it out from the profile list and the custom profile I made turns into the Embedded one ?

Adobe says this about the profiles:
"What's the difference between an embedded profile and an external profile?

An embedded profile is a camera profile that has been embedded in a DNG file (i.e., the profile data is stored in the DNG along with the image data). An external profile is a camera profile whose data is stored in a separate file on disk; this file has a .dcp extension. Otherwise there is no difference between embedded and external profiles."

So i guess to clarify, how can I turn the external profiles into embedded ones so I don't have to deal with a bunch of those external files a few months from now ?

I'm going to tread carefully here and I'm sure I'll be corrected.  "Profiles" are a function of the raw processor.  C1pro will have a different profile from ACR or LR through ACR and LR probably share the same because of their close relationship with Adobe.  As a file recognized by that raw processor it seen by the raw processing software, it assigns a profile from it's database of profiles supplied by either the raw processor or any profile you add and assign.

Even years ago we were using non-OEM (for lack of a better term) profiles suppled from guys who knew how to make them and who had an eye for color.  Magne Nilsen for instance used to make some awesome profiles for the Canon 1ds Mark II which were compatible with C1pro and I still use them today.  Actually I've recently dug out my Canon 1ds Mark II and am rekindling my love affair with that body.. I'm absolutely convinced that from ISO 100-800 it makes better files than my Canon 5d Mark II.    Anyway.. this profile is flagged in C1pro so any time I process a 1ds Mark II image that profile is applied.

Keep in mind the standard profiles provided by Adobe and C1pro and other raw processors are "general" profiles meant to 'work' in most circumstances so they're not tuned to just one type of light.  The Magne Nilsen profiles were a bit more specialized in that they're geared for higher or lower saturation.

The x-rite color checker profiles are specific profiles built to balance the colors using the specific light of that shoot.  You would not want to apply these to every image you import.. or embed them to take the place of the standard profiles provided by Adobe or C1pro..    You might create a set of profiles taken in specific light conditions, shade, sun, indoors with incandescent, etc, etc.. and use them as starting points.. but what x-rite was really designed for was to be used in place of a grey card to make a more accurate profile you can easily apply to a batch of images from a specific shoot.

These profiles are different from the Camera/Calibration area in ACR and LR.  This is where you'd enter corrections to compensate for the variance in sensors used in the same model camera.  For instance, your 645 'might' make slightly different color than a 645 that came off the line 200 units ago.  But both are supported by the same ACR/LR profile.  Camera/Calibration is where you'd compensate for the difference between sensors.

What you want to remember, is that all of the above examples are 'external' profiles.  The internal profile is a camera manufacturer starting point used by your cameras in-camera jpeg converter and LCD display, and as a reference starting point for the raw processor software to build their external profile from.

So.. you wouldn't want to change it.  It is what it is.   If you feel your color isn't right what you would want to do is determine is if it isn't right all the time or just under different lighting conditions.  If you feel, for example, that the blue channel is too saturated in general.. then you'd adjust that in the Camera/Calibration settings area.   If you feel the color is off for a for a specific lighting condition.. then this is where you'd use X-rite color checker.

And finally.. if you think you'd like to be able to embed profiles that will see all and do all under any lighting conditions.. well, that would be the holy grail of color and if you could figure that one out you could set your own price.

I hope this helps.
Logged
----------------------------------------------
http://www.BangkokImages.com

Paul2660

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 4066
    • Photos of Arkansas
Re: Color Checker Passport question
« Reply #5 on: December 25, 2011, 05:21:40 pm »

One of the features of the Colorchecker is the ability to create a "dual illuminant" profile, one that will take into
effect shadows and bright lights.  It requires shooting the passport in both lighting, in the field and then creating
the profile later on in Lightroom.  I have not tried this part yet, but you can read more about it here,  on
LL site

http://www.luminous-landscape.com/reviews/accessories/colorchecker-psssport.shtml

And from Xrite's site:

http://www.youtube.com/watch?v=mFK3NFUL7ww

As I mentioned, I have not tried this yet, but it appears you have to create it with the actual Colorchecker passport stand alone software, not in Lightroom.


Paul Caldwell
« Last Edit: December 25, 2011, 05:31:46 pm by Paul2660 »
Logged
Paul Caldwell
Little Rock, Arkansas U.S.
www.photosofarkansas.com
Pages: [1]   Go Up