Tuesday, October 14, 2008

Pentax DSLRs Color Space...

Adobe RGB

Hi Pentaxian friends,

A complete book could be written about color space definition. The color space will probably not be very important for most of us but the K20D has two color spaces available; sRGB and Adobe RGB.

In general, the color range or gamut for diverse input and output devices such as digital cameras, computer monitors, and printers are all different. This color range is also called the color space. A defined color space tends to help standardize how col­ors will appear on one’s computer monitor. For example, an image that appears on one monitor should theoretically be the same as what appears on another monitor. In color theory, the gamut or color range of a device is the portion of the visible color space that can be revealed, perceived, or reproduced. The basis for all color spaces is RGB (Red, Green and Blue).

The most common color space is sRGB. The sRGB color space is an RGB (Red, Green and Blue) color space popularized by HP® and Microsoft® because it ap­proximates the color gamut of most computer display devices. It has become the standard color space for displaying images on the internet. The sRGB color gamut shows about 35% of the visible colors. Adobe RGB was designed by Adobe® to show most of the colors achievable on CMYK (Cyan, Magenta, Yellow, and Black) printers, but by using RGB primary colors on a device such as a computer monitor. The Adobe RGB working space covers roughly 50% of the visible colors, and as a result, is an improvement over the sRGB gamut.

In the end, the goal is to reproduce the colors in the pictures taken with your camera in a way that it will look the same on the camera LCD monitor, a computer monitor, or on a printing device, as it looked in real life.

A computer monitor or camera LCD monitor uses an additive color system. This is to say that all colors reproduced on the screen are emanating from Red, Green or Blue light emitting sources. All other colors are reproduced by mixing the RGB sources. Adding all of the RGB colors produces white. Black is reproduced by the absence of any color source. The problem lies when converting colors from an RGB device to a printer using CMYK and is known to be a subtracting color system. That is a color system composed of pigments, dyes, inks, and other substances which present color to the eye by reflection, rather than emission. The sRGB color space is known to be good enough for most people. Adobe RGB is used by professional color laboratories and can yield better results in the final printing. Note, however, that sRGB will look brighter on monitors but may be limited in reproducing natural colors when transferred to a printer. Adobe RGB will give better results, in the hands of professional color laboratories and perfectionists. It is more time consuming on the printing side as very careful adjustments generally need to be made.

The default color space used by the K20D is sRGB. It is probably best to try both color spaces with your specific printing device. Use what you perceive as being the best reproduction of the image as seen by you when the picture was taken. After all, it’s all about perception.

To change the color space, press the MENU button. Using the four-way controller, navigate right ► to the Rec. Mode menu. Using the front e-dial, go to page 2/2. Navigate down ▼to Color Space, then right ► and choose sRGB or Adobe RGB. Press the OK button twice.
Thanks for reading,
Yvon Bourque
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