gradients are not smooth, free of streaks/bands

I just had this issue with a black to clear gradient over an image. I changed the black to be a mix of colors (CMYK) that's close enough to black without being 100% K, then I rasterized just the gradient and it fixed the banding issue. 

does anyone on this site even know what they are talking about!!!!  Alot of bad advice.

Banding in Gradients has to do with the limitations of printing. Check out the following from the manual: Printing gradients, meshes, and color blends in Illustrator

The banding effect has several origins:

Monitor:

The main reason why you see banding on your monitor is because you use a software calibration. Software calibration uses the LUT-tables of your videocard. LUT-tables are prone to rounding errors, bad measurements and linearity issues caused by the software. Therefore it's better to use hardware calibration available in Eizo monitors with integrated calibration device. Even the best software calibration (e.g. SpectraCal, ArgyllCMS/DisplayCal)can't compete with the Eizo hardware calibration in my experience. Word of advice: just buy an Eizo CG series monitor.

RGB vs CMYK gradients:

When you're working in CMYK color space you're working with a synthetic device profile. CMYK profiles such as Swop or Fogra39 are characterizations of offset presses. Even though a great effort has been put into the construction of these profiles they are not linear. Also sRGB and Adobe RGB1998 are actually representations of average monitor color spaces but they are linear. In short when you create gradients and want them to be very linear you should work in RGB color space. In my experience the best working space profile for gradients in ECI-RGB v2 freely available on the website of eci.org. For most practices Adobe RGB and sRGB are more than good enough.

Photoshop/Illustrator:

If you want smooth gradients in Photoshop you should use 16-bit color mode instead of 8-bit. 8-bit color mode has only 256 shades of RGB channels and 100 of CMYK channels. Photoshop 16-bit color mode provides 32768 shades for both. In Illustrator gradients span between control points, so for each control point you will have a specific color and the colors in between are rendered. The smoothness depends on the software that renders the gradients (Illustrator or your RIP-software). Also I believe the previews screens of Illustrator and Photoshop are in 8-bit mode to increase performance, you probably need an extremely powerful and expensive system to run 16-bit previews live.

Printer:

Depending on the printer technology used you will get more or less banding effects. Traditional offset and flexo printing technology should be quite linear. Digital printing and proofing is another matter because linearizations and ICC-profiles are used (like monitor software calibration). I'm a consultant specialized in digital printer calibration for sign, textile and industrial applications. Most printer calibrations are made in 2-3 hours while I usually spend around 6-12 hours to create high quality calibrations. The extra time is mainly spent in measuring the calibration targets (linearization and ICC) many times over and averaging them. This allows to compensate fluctuations of color measurements due to instability of print media, printheads and the measuring devices (spectrophotometer).

Color conversions:

Conversions between different color profiles can also lead to banding effects especially because of rendering intents used. The rendering intents are are algorithms used to compensate for differences in color gamut between different profiles.These rendering intents often amplify non-linearities of the ICC-profiles especially when the CMY channels are not grey neutralized before ICC-profiling. All these problems could be solved if the colorants of the inks could be chosen to match specific coordinates, but unfortunately this is not the case for many reasons.

Hi jamesg,

If you are seeing gradations with steps on screen (rather than in print) it could be your display screen profile and calibration that’s causing the issue. However if they really are horizontal lines (across the paper width) then it's likely a printer issue. Try rotating the image - does the issue rotate with it?

If the printer is definitely OK then it could be a screen issue - I am guessing you're using an LCD (flat screen) type and not an Eizo Coloredge or NEC Spectraview display? The Coloredge and Spectraview have a hardware calibration that stops this happening.

When calibrating and profiling "Normal" the software creates a calibration look up table (LUT) which is loaded into the computer video card, the screen is then profiled. What this means is that on the way to the display the data making up an image can undergo some pretty significant corrections (like a set of curves). This can cause "contouring" or "posterisation" (where there are not enough steps of digital detail to provide a fully smooth gradation). It's not usually dead straight lines, those are usually "banding" caused by a printer head fault.

So, in short the faults you see may not be in the file you've made, just a fault in the display system. Because frustration with this symptom in pre-press and design, Eizo & NEC came up with "hardware calibration" to solve it. They had to, because high end users were refusing to switch from CRT screens (which, generally, did not have the problem).

There is a workaround, I'll explain how to do it on a Mac. Go to system preferences / displays / color and rather than selecting a display profile, try selecting the sRGB profile, now click back into Illustrator. Does this solve the gradation problem? 

It's not going to give you good colour management, for that you must have an accurate display screen profile, but it will dump the calibration LUT so you can see your file shown without it's effect. Because you need the colour management to be active don't forget to switch back to the display profile.

I hope this helps

if so, please do mark my reply as "helpful" and if you're OK now, please mark it as "correct answer" so others who have similar issues can see the solution

thanks

neil barstow, colourmanagement.net

Moving to Adobe Color [themes]​

[Moderator - moving to Illustrator forum instead]

In which color space do You designing?

Do You know that, for example, the CMYK color gamute is much tighter than RGB? In Your gradients  may be middtones, which is not present in color space.