Hi Everybody,What's a "rich" black.My photos are posted on the web. They are also printed at COSTCO in various sizes from 4" x 6" to poster sizes. COSTCO uses a photographic printer for the smaller sizes and an ink jet printer for poster size prints.My final files are made in PhotoPaint and flattened in a TIF or JPEG format.Phil
Black at 100%K tends to be on the gray side as it's just one color. Rich black uses CMYK to create a darker black. A rich black. ie 100%K 100% CMY
I'm not sure exactly where you are going with the question. What are you trying to accomplish?
"Rich Black" means a black composed by more than one ink. The CMYK Black is a "transparent" o translucent ink (the Pantone Black is opaque), then if you use a background or a big mass of black, the result is not so dark as we want. Moreover, if the printer increase the drkness (ie, adding more pressure to the Black), the images will become darker, and all shades of black will be increased proportionally also.
Usually, most printers use 40% Cyan + 100% black for a darker black. Sometimes, it's used 40% cyan, 40% Magenta, 40% Yellow and 100% Black (it's more complex use the 4 inks for some printers), and sometimes, it's used two black plates, one for the shadows of the images and other for the background. So, there're several workaround for solve the problem.
"Pure Black" it's the opposite of "Rich Black". If you have a grayscale image, you will have a pure black only. The most evident difference is the price: one ink instead four. But also is about quality. While you can create a wide range of shades using RGB/CMYK (ie more yewllowish, more blue, more dark, more light, etc) if you use only black (grayscale) you can have a better image quality since it's only one ink and preserve better the shades and tones of the image, specially the lighter tones.
one more think: althoug for image retouch is better to use RGB (you have more shades of each color), remember that if the image will send to print, it will be converted to CMYK. Then, the colors will change. The RGB Black (0.0.0) is a really dark black, but this is not the same color when send to print. First, printers don't want to use 400% ink coverage (100% of each ink) because it's very difficult and cause several mistakes. According with the Colro Profile, each kind of paper requires a different Total Ink Coverage. It could be 300% max, 320% / 340%, etc. Those values are included on the color profile. And although you don't want to use it, and although you don't include any color profile (a big mistake but a common mistake) the file will send to print using any color profile. If you don't include any color profile, when the file is sent to CTP for print, it will include a color profile and values will change if are not correct (for example, if you use a 400% ink coverage (100% of each) surely it will be replaced automatically on almost all prepress services (usually, it's a default setting)
Like this?
Or this?
Apologies, files size limited on this site, so the quality is a little off.
Phil1923 said:...Would it not be better to use an opaque ink for black even though the CMY inks are transparent. Or doesn't it make any difference if the black ink is transparent or opaque.
No, not really. You can use one of the spot color models and pay to have a real print establishment use them. Spot colors, when actually used in the printing process, are opaque inks even though they will be screened, there is a visual difference when mixing and matching spot and CMYK printing.
Look up the subjects of spot color and CMYK printing, the inks, etc. There's a ton of info available.
Phil1923 said:When I send out brochures, etc. for my senior citizen club, I was asked to give them an sRGB file so I am not familiar with the practical aspects of CMYK printing. Tell me if this is correct.
Yes and not, it's correct since it will be converted to CMYK and sRGB provide a wide gamut, enough for a good mode convert, but the change is made for other people, not you. In other words, you don't see the final CMYK image and you don't have control of the changes. If you trust on the people who works with you, it's fine, but as a general rule we can't let other people adjust our images, change colors and make color corrections.
Phil1923 said:Pure black is not totally black because the black ink uses a "transparent" ink. Would it not be better to use an opaque ink for black even though the CMY inks are transparent. Or doesn't it make any difference if the black ink is transparent or opaque.
Although it seems easy, it's not possible. The "transparent" inks allows the mix when you print 4-inks overlapping the dots. An opaque black will produce a wrong black coverage: all dark areas will be a black patch. btw as i said before, some printers use two black colors, a transparent CMYK for text and photos, and a opaque Pantone Black for a background. Of course, that increases the price, the time, etc