How to remove thin white line artefacts when applying new art brush to circle

[johnnytheboy01]

Dear all,

I am trying to apply a custom made art brush to a circle, but for some reason there are some artefacts that appear when doing so. My art brush consists of multiple circles that I have individually applied a radial color gradient to, which were then rasterized to incorporate in the brush. When applying the brush to a straight line there is no problem, but when applying to a circle you get these thin white lines around each of the circles that make up the brush. Please see the attached image below for a demonstration of the problem.

I have tried turning off anti-aliasing or adding a black stroke to the circles before incorporating them into the brush, but to no effect. Any help would be much appreciated!

[Eternal Warrior]

The most obvious issue with your brush is that you are rasterizing it and then trying to use it in a vector based programme where you probably aren't keeping the same 1:1 ratio as when you created the original brush > Or more accurately in this instance you are trying to apply it to a circular shape..

Re-create the brush without rasterizing. If need be add the colours to the artwork afterwards.

[Eternal Warrior]

Also I found this link to give a relatively useful guide about the various brushes you can create in illustrator: http://www.bittbox.com/illustrator/how-to-make-a-custom-illustrator-brush

[johnnytheboy01]

Thank you for your answer.

The problem is that Illustrator does not allow gradients inside art brushes, hence the rasterizing. I could create a brush with colorless circles, but I'm not sure how I would be able to add these radial color gradients for each circle afterwards. The full brush consists of 1000s of circles, with different but non-random color patterns for each string of circles.

[Monika Gause]

Which version of Illustrator exactly is that? THere has been an issue with transparent pixel brushes in one of the recent versions, but it has been addressed.

On top of that: which color mode and how exactly is black defined?

and: can you go to Preferences > General and turn off the "Smoothing" setting. Does that improve the image?

[johnnytheboy01]

I'm using Illustrator CC (2015). The color mode is RGB and black (000000) is shown as "rich black".

I did not find the "smoothing" setting in my version, could it be in a different menu?

[Doug A Roberts]

i had a go at recreating this in cc2017 and did not get outlines. how did you construct the gradients initially? do they use transparency or do they go from colour to black?

[johnnytheboy01]

Thank you for going through the trouble of trying that! Weird that it doesn't happen to you, though. The gradients, from colour to black, were created using a script, part of it I will paste here:   

        var currentObject = app.activeDocument.selection;

        if(currentObject.typename != "CompoundPathItem" && currentObject.typename != "GroupItem")

            {

            if(currentObject.filled==true &&

            currentObject.fillColor.typename != "GradientColor" &&

            currentObject.fillColor.typename != "PatternColor" &&

            currentObject.fillColor.typename != "SpotColor" &&

            currentObject.fillColor.typename != "GrayColor"

            )

                {

                var currentColor = currentObject.fillColor;

                var currentRed = Math.round(currentColor.red);

                var currentGreen = Math.round(currentColor.green);

                var currentBlue = Math.round(currentColor.blue);

                // Create a color for both ends of the gradient

                var startColor = new RGBColor();

                var endColor = new RGBColor();

                    startColor.red = currentRed;

                    startColor.green = currentGreen;

                    startColor.blue = currentBlue;

                    endColor.red = 0;             

                    endColor.green = 0;               

                    endColor.blue = 0;

                // Create a new gradient

                // A new gradient always has 2 stops

                var newGradient = app.activeDocument.gradients.add();

                newGradient.type = GradientType.RADIAL;

                // Modify the first gradient stop

                newGradient.gradientStops[0].rampPoint = 0;

                newGradient.gradientStops[0].midPoint = 50;

                newGradient.gradientStops[0].color = startColor;

                // Modify the last gradient stop

                newGradient.gradientStops[1].rampPoint = 100;

                newGradient.gradientStops[1].color = endColor;

                // construct an Illustrator.GradientColor object referring to the

                // newly created gradient

                var colorOfGradient= new GradientColor();

                colorOfGradient.gradient = newGradient;

                // get current path item, apply new gradient as its fill

                currentObject.fillColor = colorOfGradient;

                currentObject.rotate(false, false, false, true, false, Transformation.CENTER);

I forgot to mention previously, but another thing that might have something to do with it is that the circles were originally rectangles that I replaced using the "convert to shape" option. Then I applied the script, and then rasterized the whole bunch to create the art brush.

[Monika Gause]

Please post a file that contains both the initial artwork and your brushes.

It doesn't make too much sense to post only a part of your process. In order to understand what's happening we will need to examine the original files.

The smoothing setting (antialiasing, whatever ... I don't remember each and every localized setting name) is in the General preferences. I have a German version, so it won't be of much use telling you that name.

[johnnytheboy01]

I had already played with the anti-aliasing setting but that didn't help. I just recreated the issue by making new ellipses, creating the gradients without using a script, rasterizing and making the art brush. So it doesn't seem to have anything to do with any previous steps...

Sorry but how do you add an attachment? I only see buttons for a picture (or a video), but that doesn't work for .pdf files.

[Doug A Roberts]

so you create the circles with whatever colours you choose, then run the script?

maybe this is something to do with colour. are they spot or process? what's the document colour mode and document profile?

[johnnytheboy01]

Yes indeed, the script then takes the colors of the circles as starting point for the color-to-black radial gradient.

Colors are process, RGB mode. Sorry but I'm not sure what you mean by "document profile"?

[Doug A Roberts]

doc profiles are what you see in the drop down list on the new document window (Print, Web etc.). even if you make changes and the profile reads [Custom], you are still just editing an existing profile. So, for instance, if you select a print document profile, then change the colour mode to RGB, you will still have a bunch of swatches in the document that were created as CMYK.

[johnnytheboy01]

The doc profile is "custom", but there is a warning sign that the chosen color mode (RGB) is different from the one defined by the document profile. I just tried and can recreate the issue as well in a CMYK doc.

[Doug A Roberts]

ah well. it was a shot in the dark.

you can't attach files to posts here aside from images. if you can share the file, use a file hosting service and post the link.

[johnnytheboy01]

OK, it was worth a shot.

I've been trying a bunch of different stuff and it really is the rastering. The thin white lines also appear when using single color ellipses, rasterizing them and incorporating them into the brush. I've tried different rasterizing settings but it never changes the outcome. However you said that it doesn't occur in cc2017? I can try and find someone that has this version, maybe that's the only way to solve the problem...

In case anyone is still interested, here is the original file demonstrating the problem:

WeTransfer

[Doug A Roberts]

this looks like a PDF saved without illustrator content. can you share the AI file?

[johnnytheboy01]

I just saved the editable pdf file of this one and no AI file. Is it bad to skip the AI format?

[Doug A Roberts]

it makes it quite hard to troubleshoot...

[johnnytheboy01]

OK, I made a new example, with simple red circles this time:

WeTransfer

Without rasterization there is no artefact whatsoever, but the rasterized brush clearly has it. At least on my screen.

[Doug A Roberts]

i get the same pale pixels around an object as you in a CMYK doc, but not in an RGB one same rasterisation settings in each one.

[johnnytheboy01]

Man, then I have no clue as to why in my case it happens both in CMYK and RGB mode...

[Eternal Warrior]

Have you tried Ton Frederiks' suggestion?

[Eternal Warrior]

Just a side thought but it depends on whats possible with scripts and your knowledge thereof:

Perhaps you could tackle this another way?

By this I mean avoid rastering by making a script that targets the gradient colours for each element in the brush after you have created the vector work?

[johnnytheboy01]

My knowledge of scripting is unfortunately rather limited... Your suggestion probably would solve the problem, though