Artistic filter: All there is to know

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Gamekiller48

Gamekiller48

Hi everyone! In this tutorial I'll take a in-depth look at the artistic filter added to Clip Studio Paint in version 1.9.4.

 

I'll go over every setting of this filter in detail, explain how to work with this filter and why some of the results don't look quite like you'd expect them to.

 

Let's get started!

The artistic filter

To illustrate the various settings of this filter, I prepared this image. A photo, a blurred version of this photo, a collection of various circles with gradients applied to them, and a rough painting of the same shapes.

 

The version on the left will always remain unaffected, while the version on the right will have the filter with the current settings applied to it.

We apply the filter by selecting whatever layer we want to use the filter on, then going to Filter > Effect > Artistic...

A window will open that looks something like this (values for the various settings might vary)

Lines only

The filter allows to process the color and lines at the same time, or separately. While processing them at the same time is a bit more convenient, there are good reasons to do it separately.

 

So before we even start, we should duplicate the layer we want to use the filter on, then select the upper layer and use the artistic filter with Process 'Lines only' on it.

 

In 'Lines only' the outcome is only affected by the first 5 settings, so we can ignore the last three settings for the moment.

For comparison purposes I set all values to 50.

As we can see in my test image, the artistic filter makes use of contrast in an image to identify where to place lines. The blurred photo has a lot fewer lines than the one in focus, the same thing applies to the circles with smooth gradient in comparison to the painted version, which has a lot more sudden changes of colour values.

Line thickness

Let's take a look at the first setting: line thickness.

While the setting does indeed change the thickness of the lines as the name suggests, that's not all it does.

We can see this the best when we enter a low value (e.g. 10) for line thickness and take a look

at the blurred photo in my example sheet: no lines show up at all - but that's not what we'd expect to see. What we would expect to see is to have as many lines in the image as for a higher value, just for them to be thinner.

Similarly the focused photo has more lines than the same image at a higher line thickness setting.

 

So, why doesn't that happen? My guess: line thickness not only affects the thickness of the lines themselves, but also how the original image is sampled. At higher settings the filter is more forgiving of low contrast (e.g. slightly blurred areas), while at lower values it only places lines at areas with extremely high contrast.

Line simplicity

In the following examples I'll lower the line thickness to 40, as it has a nice balance between line count and readability.

 

Let's continue with various values for Line simplicity

Line simplicity changes how smooth the rendered lines are.

One interesting result you can observe here is how the outline of the smooth circle changes and becomes less smooth as the value of line simplicity increases - I'm not entirely sure why that is, my best guess would be this: As the lines seem to follow along similar shades of the circle gradients (best noticable by how the lines around the circles with vertical gradient direction are alligned horizontally, while the lines around the circle with horizontal gradient are alligned vertically).

Line density

For the following comparisons I'll keep Line simplicity at 50.

 

Let's take a look at several values for Line density:

Line density controls how many lines appear in the resulting image.

 

While the idea behind the setting is straight forward, which value to choose for this setting really depends on the image in question, as apparent in my example sheet:

While a low line density (e.g. 1) works for a highly detailed photo or a simple shape like the circles, it doesn't work for the blurred photo - the resulting image is barely recognizable.

On the other hand a high value for line density becomes hard to read for the focused photo, but is exactly what you need for the blurred photo to make out some features.

Line opacity

I'll use a line density of 25 for all following comparisons.

 

Let's take a look at some line opacity values.

Line opacity is pretty self explanatory, it controls the opacity of the rendered lines.

 

The setting becomes a bit more useful if used in the 'Color and lines' process, as it is the only point at which you can influence how the lines blend in with the background colours, however as we are applying the filter for lines and colour separately, it's not as important for our workflow.

 

I suggest a line opacity of 100 in the separate workflow, as the opacity can always be lowered in the layer settings at a later point in time.

Line anti-aliasing

I'll use a line opacity of 50 in the following comparisons (mostly because of how harsh the black lines look on the screenshots)

 

Let's take a look at various line anti-aliasing values.

To understand this setting, one should understand what aliasing is first:

As all pixels on a screen are arranged in a grid, they are perfect for displaying straight horizontal or vertical lines, but have some issues when displaying lines which don't align with the grid.

In cases like these, some displaying artifacts can occur, such as the staircase-effect, which makes diagonal lines make look more like a staircase than a line. This effect is called aliasing.

Anti-aliasing are techniques which try to combat these artifacts by distorting the image information in a way that makes it appear smoother on a display.

 

In effect it mostly means blurring edges and lines, which we can observe here - the higher the setting, the blurrier the lines.

 

I suggest a rather low value for this setting, however also suggest to not keep it at 1.

Colors only

Once we are happy with the line settings we can apply the filter and change to the second layer we created previously and also apply the artistic filter to it - but this time we choose 'Color only' for processing.

In the 'color only' mode the outcome of the filter is only affected by the last three settings, so this time we can ignore all the line settings.

Color blending

Let's compare some values for color blending:

The color blending setting affects how color is blended together - this is however not to be confused from just blurring. As one can see in the focused photo example, the outcome still has very sharp outlines.

One can understand it like this: color blending tries to preserve contrast, and only affect the underlying colour.

 

This setting has a huge influence on the look and is one you should definitely play around with. Too low a value and the result will still basically look like a photo, while a higher setting makes it look more like a painting.

Color blur

I'll use a value of 50 for color blending in all following comparisons.

Similarly to color blending, color blur also blends color together, however unlike color blending it doesn't try to preserve contrast. The edges of shapes become more blurry the higher the number and much detail is lost.

 

While this might sound bad in theory, one shouldn't forget that we still have our lines layer to keep the shapes together. It doesn't hurt to use a moderately sized number here to make the result look less like a photo.

Numbers of colors - Part 1

I'll use a value of 30 for color blur in the following comparisons.

 

Now for the last, and possibly the most influental setting of the artistic filter: the number of colors.

 

Let's compare some values.

Number of colors, as the name suggests, determines how many colours appear in the resulting image. However, there are some severe artifacts associated with low values of this setting, which incidentally also happen to be the values which many of use are trying to use to emulate the toner look found in printed comics and manga.

 

One obvious artifact (or behaviour) of the setting is sever color banding, which you can best see in the gradient circles: instead of a smooth blending of colours, there are sudden jumps between colour values - which is exactly what we are going for.

 

There is however another artifact which is a bit harder to understand and less desirable, and that is that the colours themselves become more saturated at low values for this setting.

 

So, why is that? The answer is interesting enough that I'll give it a section of it's own (which you can skip if you aren't interested in the technical explanation behind this phenomenon though).

The changing colour artifact - explanation

So what causes this weird change of colour? We as users would expect the number of colours to decrease, but only for colours from the original image to show up - so where do these super saturated colours come from?

 

To understand this, we have to take a look at how the colour information in images is stored.

The colours in an RGB image are actually stored and processed in three separate logical layers. Basically one can imagine any colour image as three separate black and white images, one of which is displayed on the red LEDs in your monitor, one on the green ones and one on the blue ones.

We can take a look at these separate images by creating three copies of the original image, and changing the tone curve of each layer.

We can open the tone curve via Edit > Tonal Correction > Tone Curve...

We then want to change the setting from 'RGB' to one of the colour channels and reduce all the values to 0 by dragging down the rightmost dot on the tone curve

Repeat this for a second colour channel, so only one colour channel remains unaffected. Basically to see the red part of the image, we want to remove the green and blue channel, for the blue channel we want to remove green and red, and for green we want to remove blue and red.

If we did everything right, we'll end up with three layers looking like this.

If we now apply the artistic filter with a low value for 'Number of colors' for each colour layer separately...

...the individual layers look correct, but...

...as soon as we set the two upper layers to blending mode 'Lighten'...

...the result ends with distorted colours like we saw it for a low 'Number of colors' setting.

 

Another thing of note is that the 'Number of colors' setting within the artistic filter seems to be just the posterize function (found under Edit > Tonal correction > Posterization...), but extended to 64 values rather than the 20 available in posterization.

 

Due to this artifact, a workflow with coloured images is not advisable for low number of colours - instead I suggest a black-and-white approach, which we can then add colour back in at a later point.

Sidenote: image size

It is important to note that the artistic filter processes everything about the image on a pixel level (obviously). The consequence of this however isn't immediately apparent to us humans if we don't stop to think about what that means.

 

Imagine that we have an image that has a contrast edge that is exactly 40 pixels long, and we decide to use the artistic filter with a line thickness of 10 - the filter would trace this contrast edge, and give us a nice thick line of length 40 and width 10 pixels.

Now imagine we scaled this image down to a 4th of its size before applying the very same artistic filter to it - the contrast edge would now only be 10 pixels long, yet we would still apply a line of 10 pixels thickness to it. The result would now not look like a nice thick line, but like a dot.

 

As illustration of this point I did just that - I applied the same artistic filter to three variants of the same photo, one at full scale, one at half scale and one at one fourth scale.

 

As you can see, the result images look very different.

Keep this in mind when reading some of the values I suggested for the filter, results might vary depending on how big of a picture you are trying to apply the filter.

Number of colors - Part 2

We saw that the number of colors can cause some issues in coloured images, so we'll take another look at this setting, but this time in a greyscale image.

 

As a greyscale image doesn't have colours, we'll have to interpret the setting as 'Number of values' this time. The principle is pretty much the same, the lower the number, the fewer different shades of grey the resulting image will have.

Applying the artistic filter with the settings above will result in drastically different results, depending on the 'Number of colors' setting:

Now that looks a lot more like something you'd see in the background of a comic or manga, doesn't it?

Closing thoughts

The artistic filter is a powerful tool, which opens a whole new array of possibilities of Clip Studio Paint users.

 

But like any powerful tool, one needs to understand what they're doing with it, otherwise the results can be less than satisfactory.

I hope this in-depth look at all of the settings of this new filter shed some light on its possibilites and gave inspiration on how to use it.

 

Happy experimenting!

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