Colors on the 202 and 203 cards
The colors samples on QPcard 202 and 203 are carefully selected with digital cameras in mind
Our primary goal is to recreate natural undistorted colors from any digital camera that has a RAW option; images with correct hue; where red is red, green is green and blue is blue; photographs with sufficient saturation in all channels. We are convinced that this is the optimum starting position for time efficient image editing in RGB. Our second goal is to get the correct colors in a fast, accurate, uncomplicated and inexpensive way.
Our color correction is performed using color management and profiling at the first accessible stage in the digital picture workflow - the RAW image. In order to accurately model the profiled camera's color properties, we have designed a new high quality color target with modern camera sensors in mind. With only 35 carefully selected and individually manufactured color patches mixed from a large selection of very high quality pigment bases, we can meticulously pin-point the color behavior of almost any camera in any light.
Our calibration application compares camera performance with target colors and creates instructions for the profile on how to "move" small clusters (almost 1300) into correct position in a three dimensional color space. We control color saturation in two stages: primary control in the matrix and "soft clipping" and fine tuning in the lookup table.
QPcard 202 and 203
The design and preparation of the color card is crucial for successful color management of the camera. QPcard 202 and 203 have 35 color chips painted on a cardboard surface. The carefully selected color samples are individually mixed in order to achieve as straight forward spectral response as possible. This is very important in order to avoid undesired metameric effects that can make correct evaluation of the color performance impossible with lesser formulations.
The color samples are divided into four groups. The primary groups have 9 saturated samples of red, green and blue picked to accurately determine the spectral midpoints of the on-sensor filters. The secondary group has 12 samples of complementary colors chosen to properly graduate saturated colors. The grayscale group has 7 neutral samples of different lightness for white balancing and linearization of individual channel response. The pastel group with 7 lighter, still saturated, color samples helps fine-tuning skintones and lighter colors.
The colored patches of the cards are automatically detected and a measurement grid covering them is created. Every color patch is measured in up to 6400 spots of which 3200 outlier values are discarded. This prevents small dust particles to interfere with the measurement. As opposed to commonly existent older color targets on the market, we have intentionally kept the background white. This gives us an opportunity to evaluate the evenness of the exposure of the card. If the card is unevenly lit, we compensate in the linear RAW signal with maximum 1.5 EV, assuring high quality profiles even if the card isn't photographed in perfect conditions.
You can download a reference synthetic rendering of the QP203 here:
Adobe RGB reference tiff image of QP203, including Lab values
Beyond graycards and white balancing
White balancing must not be confused with profiling. White (or gray) balancing means fine-tuning of the balance between the three color channels red, green and blue in order to compensate for color temperature deviation. Manual white balancing, using a neutral gray target in the scene, is the best way to achieve neutral grays in the picture. However, it doesn't matter if the gray target is manufactured by Kodak, Datacolor, X-rite or QPcard; the end result is the same. The fact of the matter is that colors are only marginally corrected using white balancing. Take a picture of a colored scene with three different cameras. Include a gray target in the scene. Make sure all three pictures are perfectly neutralized using the gray target. Now check colors. Most likely they will differ quite bit. Canon and Nikon have different ideas of color appearance. And Adobe are adding color ideas with their standard profile in Adobe Camera Raw.
Color management with profiling is so much more than white balancing. In color management you not only balance the position of the color curves, you actually tweak them in order to normalize color performance in accordance with neutral undistorted colors in the photographed scene. Use QPcard 202 or 203 and QPcalibration with the three cameras mentioned above and you will most likely not notice any color difference between them.
QPcard takes picture control one step further