I have been asked the question many times before: why does my photography/image look so flat when i convert RGB to CMYK color?
Well, the answer is science.
RGB is additive color theory. Red, green and blue light when combined produce white light. When red, green and blue light are turned off, there is no color therefore resulting in black. This is how your monitor and television function.
CMYK is subtractive color theory. Cyan, magenta and yellow ink act as filters to absorb and reflect light that is reflected off paper. When light reflects off paper where no ink is applied, this is white. When light reflects where all three colors are present, no light reflects back resulting in black. Cyan ink absorbs red light; magenta absorbs green light; and yellow absorbs blue light. This is the basic theory of subtractive color.
It’s important to note that a fourth ink (black) is used to create more contrast and deeper blacks/shadows in images. The amount of black ink is dependent on the conversion process that is used, for example medium GCR (Gray Component Replacement).
RGB color uses projected light which is much more brighter than light reflecting off a substrate with CMYK color. The additive light (RGB) creates a color gamut that is much larger than subtractive (CMYK) color gamut.
Does this explain RGB to CMYK conversion for you? Please place your comments below…
[learn_more caption=”Transcript of Video” state=”open”]
Hi. This is Rick Rys from HiDefColor.com. Today we are going to discuss the conversion from the RGB color space into the CMYK color space.
[0:14] RGB is an additive color space meaning that red, green, and blue light together will create white. When red, green, and blue light are off, they will be black when it is projected onto screen, or onto a monitor.
[0:31] CMYK is the subtractive color theory meaning that the cyan, magenta, and yellow inks act as filters. As light bounces off of the paper, it reflects up through the cyan, magenta, and yellow inks, which in turn will either absorb or reflect different color wavelengths.
[0:52] The opposite of red is cyan, the opposite of green is magenta, and the opposite of blue is yellow. The subtractive colors are the gray components of the additive colors meaning that when they’re put together, they create gray, or black, or white.
[1:07] The LAB color model–let me turn this off here–is a 3-axis color system, and the LAB colors are absolute meaning that the color is identical. It’s across what’s called a device-independent, meaning that the LAB color space is the only way for you to communicate different colors across different devices.
[1:35] Now, it is a 3-axis system. The first axis, the L-channel, or lightness goes up and down the 3-D color model, and it consists of white to black, and all of your gray colors will be exactly right down the center.
[1:49] All your neutral colors will be relatively in the center of this axis. The A-axis goes from a cyan/blue color across to a magenta/red color, and the B-axis goes from blue to yellow.
[2:07] Within this area, we’re going to plot our visual or reproducible colors based on the gamut or the profile of the device we have. I’m going to turn on the sRGB color profile. Most monitors display in sRGB; sRGB is preferred for any type of Internet or Web application.
[2:27] And look at this thing spinning here. And you can see the volume of the colors that you can reproduce from this additive color model. Obviously, since it’s dealing with projecting light, they’re very bright colors and they’re very saturated.
[2:44] Now when we bring in and display the CMYK GRACoL color profile, you’ll notice when I turn it on the sRGB encompasses the whole CMYK color gamut beside this area of cyan and greens through here.
[3:03] If you look down on the color model, you’ll notice that the circumference of the model is projected along the bottom here. You can see the outside perimeter of the sRGB color profile.
[3:17] The brighter colors are just not capable of being reproduced with the CMYK color gamut. You can see what happens when you get these real dark blues. There’s no blue for you to hit in a CMYK color model.
[3:30] What I’m going to do is I’m going to take our sRGB color profile, and I changed the opacity, so you can see the difference that we’re dealing with here. As you can see the volume of color on the RGB color profile is nowhere near what can be reproduced in a CMYK color profile.
[3:53] So what we have to do is we have to do our best job of remapping these colors, or what is known as tonal compression, to bring this sRGB color model into the CMYK color space.
[4:06] This is why–I’ll stop right here–when you look at a blue sky, you may always be disappointed with the results you get because when the photograph is in RGB, you’ve got all these deep bright blues and more of the colors you see in the horizon.
[4:30] When they’re converted to CMYK – you’ll notice when I change opacity, all those bright blues have to be condensed into this little area here of the blue hue that’s reproducible in CMYK.
[4:42] There’s a sacrifice there, and that’s where you get into using either relative rendering intent, or the perceptual color intent. That will help you resolve some of issues you have with converting your dark blues into the CMYK color space.
[4:58] Let’s turn this opacity back up, and you’ll get an idea, again, of what we’re dealing with here. We need to take all of this color and condense it into this little area right here.
[5:12] And this is the GRACoL color profile. The GRACoL color profile has more colors than the SWOP profile, so we’re going to get a better representation of some of those more juicier RGB colors when they’re converted to CMYK.
[5:27] So let’s bring this up again and show you the difference of converting all of this into this little area here. This is why color management is so important and knowing what profiles you’re dealing with.
[5:41] Your safest bet is using the sRGB color space and converting into the coded GRACoL profile. Keep in mind that dealing with your print provider, they will produce, or they will provide the correct color profile based on their printing condition.
[5:58] A profile is a recipe, or the characteristics of a particular printing condition. Based on the press, the inks, and the paper that they use that will produce a profile.
[6:10] Well thanks again for tuning in. I hope this clears some things up. If you have any questions, please feel free to leave a comment on the blog. And we will see you next time.
We’ve all been talking about cross-media publishing for the last fifteen years or so. I know it’s been on my radar for a long time. Finally, there really is a great form of cross-media publishing that really is quite simple and very effective to your marketing strategies.
The answer: QR Codes.
QR codes are scanned by smart phones. Visit: http://get.beetagg.com in your mobile browser and automatically download QR Code reader software.
This VIDEO will show you how to get the most dynamic and sharpest images in your printed marketing material. This is a two-step Photoshop sharpening technique that will show you how to create the sharpest images without creating noise in smooth midtone areas of your photographs.
This is one of my favorite Photoshop sharpening tips in reproducing beautiful photography on press. All images are not as sharp as they can be when converted from raw files. These days there is a lot of post image processing that needs to be done with digital images. One of the key things that is overlooked is how sharp the image is. We now work with incredibly sharp LCD displays and images seem to jump off the screen. Unfortunately, when an image goes through the RIP (raster image processor) process in prepress, the image is naturally softened in the screening process.
Remember, your photography is only as good as the printer you choose!
Let me know what you think. Please leave your comments below…
[learn_more caption=”Transcript of Video” state=”open”] Hi. This is Rick Rys from HiDefColor.com.
Today, we’re going to talk about one of the greatest Photoshop sharpening techniques to take your photographs from a good photograph to a great photograph.
[0:13] Notice the transition there. This will demonstrate how to take a great photo and make it into a true high definition color print when it’s printed on press.
[0:25] All right, let’s get started here.
[0:27] As you can see, I am working in the LAB color space right now. You can work in RGB and get the same results. I prefer using LAB. Just keep in mind you want to convert to CMYK at the very last moment so always work in RGB or LAB.
[0:43] First things started, we’re going to do a Select All and we’re going to copy and create a new Alpha channel here and paste our document or image into our new Alpha channel.
[1:03] We select that and we’re going to Filter, Stylize and click the Find Edges. Now what Find Edges will do is look at all the sharp contrasting points in the image and basically highlight those and create a line drawing for you.
[1:21] From here, we’re going to go on to our curves, which is our Command M and we’re going to alter this channel.
[1:30] First thing you want to do… In a nutshell, what’s happening here… We’re going to sharpen the darkened areas. The white areas will not be sharpened so we’re going to maintain our smooth, crystal clear, creamy midtones and not create any noise in there from excessive sharpening.
[1:49] First thing, you’d want to grab our shadow end of our curve and bring this over all the way up to 50%. At the same time, you’d want to take our highlight end of our curve and bring this up to about 20% or so.
[2:09] You can see right now we’ve created a much higher contrast now in this line drawing. And again just to make another adjustment here, we want to make our black areas a little wider as possible so we’re going to add some more density to that black and kick it up. You can see they’re almost intersecting each other.
[2:29] At this point, we’re going to click OK and we’re going to go into Filter and create a Gaussian Blur on this image. The blur will spread the black areas to create a subtle transition between these smooth areas and the sharpened areas.
[2:50] So, select Gaussian Blur and use anything… I prefer to use two and a half pixels. That seems to work fast for me. So, select 2.5 pixels and click OK.
[3:04] Now back to curves again. You could see we softened up the image.
[3:07] Now we go back to curves and harden up that edge a little more. So we’re going to bring our shadow end of our curve all the way up to 50% again. You could see how much darker we made that so we’ll get more sharpening in the areas. There is no information in our white areas here so those areas will not be affected by the Photoshop sharpening filter. Click OK.
[3:32] At this point, we’re going back to our full color image and go to Select and Load Selection. Notice we’re going to select our Alpha channel that we’ve created and click OK. Now that selection is brought to place. We’re simply going to hide the selection just to save on our eyeballs there.
[3:57] And now we’re going to do our sharpening. The selection is going to just isolate the areas that we want to sharpen. Go to Filter, Sharpen and I’m a huge fan of Unsharp Mask. It goes back to the old days of running the old color drum scanner. At this point, I’m going to play around with the amount.
[4:21] Now the amount is how much the adjoining pixels are affected. I like to go real high on this number, anywhere between 150 and 200. For this tutorial, I’m going to select 200 and it’s a high number but keep in mind we’re only affecting those images in the selection itself.
[4:41] You’d want to keep the radius anywhere between half a pixel to one to one and a half. If you go any thicker, you’ll create a severe halo effect around your images. If you’re looking for an artistic point of view, you may want to do that but I would not ever recommend doing that. So we’re going to stick to one pixel.
[5:06] Our threshold determines which pixels are sharpened and which are not. A higher threshold value means that there’s a huge contrast difference between pixels that are affected. Since we have our selection, it’s a moot point so it really doesn’t matter. So I’m going to stick with a threshold of zero.
[5:26] You can see as I move through the image and click on and off, you’ll notice that there is a great deal of sharpening happening in the contrasting areas but look at the midtone areas. They’re perfectly clean and not affected at all. Just an incredible cool little tool to utilize to create dynamic looking photographs. So click OK and we are done.
[5:53] At this point, we’ll go ahead and save our image and just to show you up close, we’ll zoom in here and you can see the difference between the two. Turn on… And turn it back off again… And turn it back on. Just an awesome looking sharpening job.
[6:15] OK, thanks for tuning in. Look back for more tutorials in the future. Take care. [/learn_more]