RSA Gray Balancer

[CGPhillips4]

I've been experimenting with the RSA Gray Balancer in PhotoKit Color (especially after Jeff's plug that it only does good, never bad!). I've been having mixed luck, so I wanted to see if I understand how to use the tool correctly.

First of all, I'm shooting raw (and converting through ACR), so I get my white balance in the ballpark before converting to the final psd or jpeg. My question is, do my raw tweaks influence the response of RSA -- in other words, does the gray balancer try to undo what I might have done? Two examples I've been struggling with:

1. An indoor portrait shot under bounced flash. I make my raw adjustments to get the skintones where I want to see them (a white shirt is involved, so it's tough to work around the clipping). When I run RSA Gray Balancer, a slight yellow cast seems to be produced.

2. Outdoor scenes with saturated color. In some pictures of a red wagon in a pumpkin patch, I've boosted the saturation to get the orange tones where I want them. When RSA is run, a slight green cast is introduced (sort of looks like a 1970's color print).

Any thoughts on what I should be doing differently or more appropriate uses of the tool would be appreciated!

[louisb]

Same for me .I have had NO success at all with rsa. It always introduces an unacceptable color cast instead of neutralising the image. Useless for me so far.
Louis Bouillon

[Bruce Fraser]

Louis and CG, could you send me some examples of images where it fails? You can email them to bruce@pixelgenius.com, or let me know where I can download them.

[Martin Evening]

CG,

Please do send Bruce an example of the images that you mentioned and CC me if you can at: martin@pixelgenius.com.

What I would say is that using RSA after you have done a raw conversion could well be counter productive. The main reason for designing the RSA Gray balancer was to have a tool for dealing with images that could not be color corrected by better means. i.e. film scans where the colour is off or any other image where the colour is fixed and you need to remove a cast. If you are shooting with a professional raw workflow then the logical thing to so is to set the white balance and make a calibration using a color chart for the lighting setup you are working with and use these settings to apply to all images in Camera Raw. You do not need RSA in this type of workflow.

In Photoshop there are several auto colour tools: Auto Levels, Auto Color, and Match Color Neutralize. These generally do a good job of making an automatic correction or have little affects where no correction is necessary. We experimented with out own, different methods and reckon that the RSA corrections have the capability to analyse and correct deep casts more effectively. With any auto process there is no way to produce 100% successful results every time. And this is one reason why we provided three different RSA tools, to take into account the demands of different types of image.

Hope the above notes help explain more the philosophy behind these tools and how they are intended to be used.

Martin

[wjkotze]

I have had the following experience with RSA:

-RSA identifies the colorcast correctly and based on this creates the correct filter to counter the cast. The strenght of the correction is however way over the top and I normally have to reduce the opacity significantly.The process is very simple because you simply reduce opacity until you get the optimum result.I assume that it is an unrealistic expectation that you will always get perfect results at the default opacity setting.

[Bruce Fraser]

In addition to what Martin said, bear in mind that RSA is a global correction. It won't work in situations where you have different color casts in the same tonal range, as you might get in mixed-lighting situations. If the image can't be fixed by a global curve, it's not a candidate.

[CGPhillips4]

Bruce and Martin-

Thanks for the replies, I have e-mailed sample files. I think I misunderstood the best use for the Gray Balancer, which, as Martin suggests, is well-suited to addressing cast problems in scans and jpegs. I was trying to insert the RSA Gray Balancer into one of my standard image-processing actions that I use to btach process all captures. For captures I have done in raw, it sounds like it might be best to apply my own corrections and try the RSA Gray Balance on an as needed basis. I think I got carried away by Jeff Schewe's enthusiasm!

Best,

-Charles