None of these color spaces are better or worse than the other, have different uses, in each different colors are formed differently, llmándose the RGB additive color and subtractive CMY ... no, I have not forgotten about the K and I will explain later.
The human eye is able to capture many colors, or rather many shades of different colors, starting with red and ending with violet, this response to their wavelengths, but as a matter of physics, leave that for another time that is required.
Red - Orange - Yellow - Green - Blue - Violeta
In the above chart we can see an example of the scale of the visible colors, and how their transitions.
Synthesis Additive color, RGB:
This mode of generating colors is characteristic of the electronic media , TV's, monitors, scanners, screens of cell phones, sensors, cameras, etc..
These devices or capture the colors using the three additive primary colors, red (Red), green (Green) and blue (Blue). They are called additive because when you add to 100% the result is white and each channel will tell .
Color Additives
programs in photography and digital media in general, each R, G and B is supported by 01 bytes, ie 08 bits, then the amount of shades for each RGB channel is 2 ^ 8 (two to the eighth power), which equals 256, (0 to 255).
So, the red channel on the most will be represented by the number 255 and fully off is represented by 0, the same for the other two channels. If each channel has 256 possibilities or different tones, between the three channels we RGB 256 x 256 x 256 = 16,777,216 (sixteen million, seven hundred seventy-seven thousand, two hundred sixteen) different colors.
As we saw R + G + B = White (white) and additionally if we mix R + G = Yellow (yellow), G + B = Cyan (kind of blue), and B + R = Magenta (a kind of pink).
not forget that in this case we are adding colors adtivos light as when we turn to the maximum three channels, we obtain the maximum brightness is white.
These three colors Cyan, Magenta and Yellow (CMY) are complementary to RGB and Yellow is the complementary Blue (and vice versa), the Magenta is the complement of Green, and Cyan is the complement of Red .
subtractive color, CMY:
This mode of generating colors used in all print media , newspapers, magazines and general paper, basing its debut on cover the paper with colored inks CMY.
In subtractive color, the color white is taken up first by the color of the substrate (paper) and the temperature and intensity of light that illuminates the role. To be putting more and more ink, we will be covering the "WHITE" and putting darker each time, ie we subtracting light. Theoretically
by mixing C + M + Y should get Black (K), but since the industry has achieved so far obtained pure CMY pigments total, we get a very dark brown, never black, hence the necesisad to introduce a black channel, but not in any way.
Subtractive Colors
Before you learn how to generate the black color Note the issue of additional remains, and that by mixing Y + M = Red , M + C = Blue and C + Y = Green.
The letter K representing the black color is not black but Key.
Well, now we know that the RGB color space (additive) is used in electronic devices such as cameras and monitors, and color space CMY (subtractive, and core) is mainly used in printing, it is important we know that not all colors represented in RGB CMY can be passed, as the brightly colored "painted" with light in a good monitor can not be represented paper and inks.
In a good program like Adobe Photoshop can do the conversion from RGB to CMYK, but is not as simple as changing the color space, in any case this post is not a tutorial on how to do, but what I explain is how to generate the color black.
Well, to convert to CMYK, as well as having to fix our black and white points, correct the colors that are very different from the original RGB, one thing we must do is decide GCR, this will depend on the type of printing , the type of paper and a number of additional printing variables.
Grey Replacement Components, GCR:
is where is the fourth channel (K), is where we go from CMY to CMYK, we see a bit: If we plot the amount of ink would be used if the combination of C + M + Y was really black.
CMY
Here we see that we're using 07 drives, and cyan, magenta ink 10 units and 05 units of yellow ink, ink 22 units in total, then the process of GCR is to take equal parts of each ink CMY and replace them with black ink ... see:
GCR to switch CMY to CMYK
Taking 02 units each of CMY inks, we can replace them with 02 units of black ink, K, and get better definitions given in the shadows and have replaced 06 units of color ink (02 each), with 02 units of black ink.
after GCR So now have the following:
Moderate GCR, saving 04 units of ink
And why is it important to mention saving ink? ... think of the circulation of a newspaper, which only saves ink, black ink cost is less than the color, then this is where the GCR matter much.
The following chart GCR will apply a more aggressive, so we replace 12 units of ink (04 each), for 04 units of black ink, that is an effective saving of 08 units of ink.
Obviously, different applications of GCR affect the color gamut and contrast of a printed photo, but that's more a matter of digital prepress and offset, this being a blog about photography.
GCR Aggressive
Conclusions:
The pictures always work in RGB, if one dominates Photoshop and concepts digital prepress and printing, can venture to make the change from RGB to CMYK, otherwise leave this responsibility to the prepress workshop they are using. Obviously only if you are sending the photo offset printing.
RGB: used in your camera, your scanner, your computer, your monitor, in its editing software. The white color is obtained by the sum of the three channels, and its total absence BLACK (color display)
CMYK: is used only to bring the offset printing photos . The white color is obtained by the absence total ink (color paper), and BLACK by saturation of them.
I hope the information will be helpful, until next post!
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