Black vs Black

[Stormyj]

So I just noticed something and maybe somebody can educate me on color. When you look at blacks, rgb is r=0,g=0,b=0, and cymk is c=0,y=0=m=0,k=100. Now both are black, and on corel palette, they are as black as they can get, but cmyk is not pure black. Can someone elaborate on why this is and explain the theory behind this.

 

[AF]

What do you mean when you say cmyk is not pure black? 100k is exactly pure black unless you have a different issue?

Rich black, super black and pure black (and overprint black) are different ways to represent black on a screened image. Screen printers and offset printers would understand when to use these, not so much of a concern with an inkjet printer (trapping etc).

 

[visual800]

The value for CMYK I use is 50-40-40-100. When we use this our blacks are richer when we get our prints back. You can google it and see lots of other values for CMYK black but this one works for me

 

[John Butto]

K plate

This topic is difficult to explain in a paragraph but here goes.
When RGB (no black) are put together you have a muddy dark brown. When the K (black) is added over top you get the blacker blacks like Visual800 is talking about. RGB is added color where the color is projected to your eye, while cmyk is subtracted color which is reflected to your eye. All or most monitors, cell phones screens, tv's and so on, are rgb so what you see is not what is going to be printed out unless you have it set up on the program to show you this change. If you take a red circle, green circle and a blue circle and overlap them slightly the very middle is the dark muddy brown, which will look black on the screen, the other overlapping colors give you the spectrum of the colors mixed, magenta etc. By adding the black over the top is where you get your deep blacks.

 

[bigben]

This topic is difficult to explain in a paragraph but here goes.
When RGB (no black) are put together you have a muddy dark brown. When the K (black) is added over top you get the blacker blacks like Visual800 is talking about. RGB is added color where the color is projected to your eye, while cmyk is subtracted color which is reflected to your eye. All or most monitors, cell phones screens, tv's and so on, are rgb so what you see is not what is going to be printed out unless you have it set up on the program to show you this change. If you take a red circle, green circle and a blue circle and overlap them slightly the very middle is the dark muddy brown, which will look black on the screen, the other overlapping colors give you the spectrum of the colors mixed, magenta etc. By adding the black over the top is where you get your deep blacks.

wow, thank you for the information.

Je vais me coucher moins naiseux ce soir (french/quebec expression that will be ''I will go asleep less dumb tonight'' in english).

 

[synergy_jim]

you are talking cmyk rich black vs pure black. Rich black ( c-40 m-40 y-40 k100) is what we use when we want a really deep black. pure black always looks like a washed out shade of gray.

also if you use RGB black and save the file as RGB the RIP will usually convert to a rich black.

 

[Stormyj]

Well thank you for the info guys.

 

[J Hill Designs]

actually RGB is subtractive (hence 0,0,0 = black) and CMYK is additive (hence 100,100,100,100 is black)

 

[vid]

CYMK Black is not black, Black. It’s Process Black. All the colors in CYMK printing have some transparency to them, including the black (K). This is so they can overlay each other to visually mix and offer a wider gamut of color when printed. Solely using K to define a black in a CYMK workflow will result in a really dark gray appearance when printed on white. A double hit or second application of Process Black will make it darker because that lessens the transparency of the ink.

To expand on the mechanics of the RGB and CYMK color models —

RGB is a subtractive color model based on the effects of light. The less light one sees, the darker the object appears.

CYMK is an additive color model based on the effects of pigment. The more pigment there is, the darker the object typically appears.

On your computer monitor, an RGB device, the CYMK color palettes are represented by some calculation that someone in a dark room in Ottawa, Canada thought would best represent the effects of the final printed piece using K (black) ink — but, defined it using the RGB color model for the sake of displaying it on the computer monitor. Usually, the difference in these blacks can be seen in a side by side comparison on your monitor. Of course this depends on the resolution and calibration of you monitor, and the accuracy in which the palettes were built.

For output, because one cannot print light, the RGB color model is converted (RIPped) to a CYMK color model. Again, someone in Ottawa — where Corel is built — defined an equation that would convert the RGB color to something that could be represented by CYMK for printing. (Probably, there’s some international standard that legislates color conversion charts somewhere, but I’m still going to credit the Canadians for this.)

Because the R-0, G-0, B-0 black is not seen as a transparent black, it is calculated to use all of the colors of the CYMK ink set. These equivalent values are calculated to offer a neutral black dense enough for efficient CYMK printing.

To mimic this in a CYMK work flow, one can define a rich black by adding CY and M to the Process Black (K) to increase the density (more pigment) of the ink that is printed. — as noted by the formulas in previous posts. This adjustment is balanced to get the best effect with the least amount of ink. The dry time of the inks is the primary concern when defining a CYMK rich black.
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Sooooooooooo, the bottom line difference, between the blacks in RGB and CYMK color palettes is density and transparency when printed. When viewed on the monitor, the difference is calibration and resolution of the software and monitor.
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[bob]

CYMK Black is not black, Black. It’s Process Black. All the colors in CYMK printing have some transparency to them, including the black (K). This is so they can overlay each other to visually mix and offer a wider gamut of color when printed. Solely using K to define a black in a CYMK workflow will result in a really dark gray appearance when printed on white. A double hit or second application of Process Black will make it darker because that lessens the transparency of the ink...

Sort of...

The best black can ever be in RGB is whatever color your screen is when it's turned off. Which is usually a long way from black. On the other hand, white in RGB can be really white displayed albeit at some particular temperature. Unlike black, of which there is only one, there is no such thing as absolute white.

Conversely, in an additive CMYK environment, K is black but white is whatever color the media might be or, if you're printing white, whatever tone of white you might be using. K is truly black but it's difficult to lay down enough of it. That's why offset presses resort to jumbo rollers when attempting to lay down a large field of black.

That being the case, as you said, a bit of CMY can added to the K to help it along. Enough to lay down enough ink but not so much that any of the CMY overpowers the K and produces some dark muddy tone.

 

[rdm01]

actually RGB is subtractive (hence 0,0,0 = black) and CMYK is additive (hence 100,100,100,100 is black)

RGB is additive, when you add them all up you get pure white (light). CMYK is subtractive, when you take out all CMYK you have pure white.

 

[J Hill Designs]

RGB is additive, when you add them all up you get pure white (light). CMYK is subtractive, when you take out all CMYK you have pure white.

in my defense, physics class was a long time ago

 

[John Butto]

in my defense, physics class was a long time ago

Physics class is in room #102, universe type stuff, you are looking for Chemistry in room #101 which deals more with of the properties of ink.

 

[J Hill Designs]

Physics class is in room #102, universe type stuff, you are looking for Chemistry in room #101 which deals more with of the properties of ink.

I learned the additive vs subtractive color difference in high school physics...

 

[rdm01]

Mine was physics as well. At least in high school. Don't remember where we dealt with it in college.

 

[John Butto]

I learned the additive vs subtractive color difference in high school physics...

Well when I took physics TV was still in black and white.

 

[chillGMS]

The topic of color can be somewhat difficult to explain without visuals.

In the print world or as referred to as subtractive color, inks or pigments are used to filter light. White light is made up of Red, Green, and Blue light. Black is the absence of all light.

When laying down a pigment or ink such as Yellow, it's filters out the Blue light by absorbing it allowing Red & Green light to reflect back to the eye creating the visual sensation of color as yellow. Magenta subtracts the Green light, Cyan subtracts the Red light. In theory, if the pigments were 100% pure and they filtered 100% of the light, you would achieve a rich black when overprinting Yellow, Magenta and Cyan, but in reality when overprinting Yellow, Magenta and Cyan, it becomes brown in color as some of the light is not absorbed and it reflects back to the eye.

 

[John Butto]

visuals

The topic of color can be somewhat difficult to explain without visuals.

In the print world or as referred to as subtractive color, inks or pigments are used to filter light. White light is made up of Red, Green, and Blue light. Black is the absence of all light.

When laying down a pigment or ink such as Yellow, it's filters out the Blue light by absorbing it allowing Red & Green light to reflect back to the eye creating the visual sensation of color as yellow. Magenta subtracts the Green light, Cyan subtracts the Red light. In theory, if the pigments were 100% pure and they filtered 100% of the light, you would achieve a rich black when overprinting Yellow, Magenta and Cyan, but in reality when overprinting Yellow, Magenta and Cyan, it becomes brown in color as some of the light is not absorbed and it reflects back to the eye.

Post #4 has the visual for you, hence the brown. I guess your eye did not see it. In theory we think we see color, but that is something our human brain tells us. Other creatures on earth see those objects differently. Does a bull see red or just a flat face creature waving a dark object around.

 

[chartle]

On my roland I just used to pick MAX impact in versaworks. for my mimaki I have to juice up the black with at least 35,35,35,100.

 

[gabagoo]

Man I hate when I forget to check the blacks coming off of illustrator files ( 0 0 0 100 ) prints like rusty dark brown yuck!!!