Mastering the fill tool: ② Closed area fill




Compatible with Clip Studio Paint Ver. 1.10.2


[1] What is “Closed area fill”?

“Closed area fill” is an option to configure how the area surrounded by the tool will be filled.

The sub tools “Refer only to editing layer” or “Refer other layers” can fill in areas with the same color, when they are surrounded by outlines.


These areas that are surrounded by a line drawing is referred to as the “Closed Area“. This refers to areas (seen here in red) that can be filled by clicking inside of them with the [Fill] tool.

However, in actuality, closed areas often have very complex shape, and therefore it is more difficult to fill in such areas just clicking on them.

The [Closed area fill] is an option that can fill in these intricate closed areas effectively.


The two sub tools that utilize this option are the “Enclose and fill” tool and the “Paint unfilled area” tool.


[2] Sub Tool “Enclose and fill”

“Enclose and fill” is a sub tool that can fill in all the areas that are enclosed within a selection.




■1. How to enclose an area


Among the four circles below, the one in the lower right will not be filled because the range of the “Enclose and fill” does not include the lower right line to satisfy the requirements for this part of closing an area.

(Depending on the settings of the “Target color”, areas that are part of the selected range might be filled in. For details on the [Target color] , see “[4] Target color".

Firmly enclose the closed area you wish to fill in.

On the other hand, for closed areas you do not want to fill in, it will not be filled in when just enclosing them partially, so you do not have to avoid completely.




■2. Area scaling


“Enclose and fill” is a sub tool that can fill in all narrow closed areas that are enclosed in the selection.

In the initial settings, [Area scaling] for [Scaling mode] is set to [To darkest pixel] in order to not have color overflow from the closed areas in case of filling in highly concentrated locations.

In case color overflows to the nearby areas, please check these settings.




■3.Color margin


There can be seemingly un-colored areas that are actually not completely transparent in areas that are not filled in an anti-aliased drawing.


In such cases, if there are any transparent areas, no matter how small, they can be painted by using the [Area scaling].

For example, in very narrow parts such as the hair, there may be parts that consists of only such semi-transparent lines.

If there are no actual transparent parts (meaning that there is no object to fill) like this, it can not be filled in with the [Area Scaling].

In this case, you can adjust this by changing the value of the [Color margin].

In the following case, changing the [Color margin] to 80 has filled in the area neatly.


<The Color margin of which color?>

The Color margin is the difference between the color to be filled and the color that makes up the closed area.

In this case, since the “target color” is [Only transparent], the transparency margin will recognize the area to fill.

The color with thin anti-aliasing will be filled in with the transparency margin, since the color’s opacity has become low.

For details on the [Target color] , see “[4] Target color".


[3] Sub Tool “Paint unfilled area”

“Paint unfilled area” is a sub tool that can fill in all the area that are traced with it.

Since it can be used similar to the pen tool, it can work with more complicated parts than what the “Enclose and fill” tool could.




■1. How to enclose an area


The way in which the area is selected is the only difference between the “Paint unfilled area” tool and the “Enclose and fill” tool.

When tracing with the “Paint unfilled area” function, that area is shown in green. Only the enclosed areas that exists within it will be filled.

Similar to “Enclose and fill”, parts that are not enclosed within the green selection would not be filled.

(Depending on the settings of the “Target color”, areas that are part of the selected range might be filled in.For details on the [Target color] , see “[4] Target color”.)




■2. Size


Since “Paint unfilled area” can have its setting modified similar to pen tool, it is capable of filling very intricate areas.




■3. Area scaling and Color margin


Since “Paint unfilled area” is configured to fill in narrower areas rather than “Enclose and fill”, “Area scaling” is set to off and “Color margin” is set to a larger value in its initial setting, to prevent overflowing to other areas.


[4] Target color

With “Refer only to editing layer” and “Refer other layers”, the same color clicked in the tool will become the target to fill.

Sub tools that use “Closed area fill”, such as the “Enclose and fill” and the “Paint unfilled area”, will select the color or the target for filling that composes the closed area at the “target color”.

Depending on the settings, it can be used for color changes for not only the transparent unfilled areas, but also for black and white unfilled area.

Enclosed with the pink line and filled with red, this will explain the differences for the filled areas depending on the “target color”.

To make it easier to understand the layer to fill is placed above the line drawing.

For figures that are drawn on the “Reference layer”, anti-aliasing is turned off for all figures except ④.




■1.Target all colors


Within the enclosed area, the parts that are closed areas within the selection would be filled no matter what color they are. In this case, the area to be filled includes internal transparency and colors alike.

For figures such as ⑤ and ⑦ that do not include full transparency or another color, they are colored completely, including the somewhat transparent parts that they have.


[POINT: Be aware of drawings with anti-aliasing]

Drawings with anti-aliasing will be filled in when enclosing the entire drawing. However, if only a part is in range, only those parts will be filled. In case of plains, only the edges will be filled.

When enclosing only a part of an anti-aliased drawing, there will be situations where semi-transparent, transparent and black (color) etc. are mixed in the range, and thus create many small closed areas.

If you enclose the whole drawing, all of the drawing will be filled, as all of it is within the enclosed area.


[POINT: Be aware of filling opaque areas]

“Opaque” areas, depending on the “Color margin” settings, may be evaluated as transparent and will not generate closed areas, and thus remain unfilled.

Even if anti-aliased drawing is part of a certain range of selection, the same phenomenon might occur and you can avoid it being partly filled.




■2. Transparency only


Within all of the enclosed area, only the transparent areas within an enclosed area will be filled. This setting is set to the initial setting of “Enclose and fill” and “Paint unfilled area”.




■3. Area surrounded by transparency


Within the enclosed area, closed areas surrounded by transparency will be filled in regardless of the color of the area.

Unlike “Target all colors”, if there is a transparent area inside as it is in figure ③, ④, ⑨ and ⑩, the transparency within a figure will not be filled in as it is part of the surrounding transparency.


[POINT: Be aware of thin drawings]

If you enclose only a part of a thin line, the behavior of the filling will differ depending on the setting for the [Close gap] function.

In case [Close gap] is activated, the closed area may be generated within the surrounding transparent area and thus painted in depending on the line width of the target and its value.

In case [Close gap] is disabled, the closed area will not be generated, and thus not be filled in.




■4. Only black


Within the enclosed area, only the black areas that are closed in completely will be filled in.


[POINT: Be aware of drawings with anti-aliasing effects]

Like in ④, anti-aliased drawings with thin semi-transparency will not be filled with this setting, and therefore resulting in unfilled areas.

If the lines as shown on the left side, there will be unfilled areas.

In case the area to fill is wider, as shown on the right, it may seem like it was filled in completely, but gray portions at the edges of the drawing still exist, which means there are unfilled areas there.


The [Only black] function can be used when trying to remove dust from a scanned draft by setting the drawing color to “Transparent” or “White”.




■5. Area surrounded by black


Within the enclosed area, the closed areas surrounded by black will be filled regardless of their color.


[POINT Be aware of drawings with anti-aliasing effects]

Drawing with anti-aliasing, like in ④ may not lead complete fills for semi-transparent area. As shown within the circle, there will be closed-in areas surrounded in black that are not properly colored.

In such a case, you can adjust the [Color margin] so that thin, semi-transparent areas will be recognized as black and thus establish the closed area. Configure “Area scaling” simultaneously and set “Scaling mode” to “To darkest pixel”.


  • ”Color margin”10/No “Area scaling”

This will not recognize a closed area surrounded by black, and therefore will not fill in the area.

  • ”Color margin”30/No “Area scaling”

The gray area will be recognized as black as well and the closed area will be filled.

  • ”Color margin”80/No “Area scaling”

At this point the range for the margin is too large and the thin gray area will be excluded from becoming part of the closed area, resulting in an unfilled area.

Using [To darkest pixel] from the [Area scaling] will increase the area to fill while also preventing any overflow.


  • ”Color margin” 80/“Area scaling”10 → “To darkest pixel”




■6. Only white and transparent


Within the enclosed area, only the white and transparent closed areas are filled.

Like for ⑨, a drawing that consisted of white or transparent areas, are composed only of filling targets, so they do not become closed areas and can not be filled.




■7. Area surrounded by white and transparency


Within the enclosed area, parts that are closed areas within the selection would be filled no matter what color they are.




■8. Treat pale transparent as transparent


Within the enclosed area, the parts that are closed areas within the selection would be filled no matter what color they are. In that case, the areas to be filled include transparency and the colors within them.

“Treat pale transparent as transparent ” is a newly added setting to “Target all colors”. Actions other than filling thin semi-transparent areas will be considered the same as the “Target all colors”.


[POINT Be aware of drawings with anti-aliasing]

Similar to “Target all colors”, drawing with anti-aliasing effects, will fill everything if the entire drawing is enclosed, but if only partial areas are enclosed, only the areas within the selection will be filled.

In case of plains, only the edges will be filled.

“Treat pale transparent as transparent” allows to distinguish semi-transparent areas as transparent and is able to fill in more cleanly as compared to areas that were not filled with the “Target all colors” function.

However, it might also fill semi-transparency on the outside, which would make the surrounding area a different color and it may look as if there as overflow.

In case you wish to fill the inside of a line cleanly, select other setting and combine/use “To darkest pixel” from the “Area scaling” function.




■9. Other than transparent and inner transparency


Within the enclosed area, this fills in the non transparent color areas and inner transparent areas that are enclosed.

While basic function is same as that of “Target all colors”, processing slightly changes when anti-aliased drawing enters the range.

With “Target all colors”, there are cases where areas that are part of a selection are filled due to the value of the “Color margin”.

When using “Other than transparent and inner transparent”, areas are not filled, regardless of the value for the “Color margin”.




■10. Open areas and other than transparent


Within the enclosed area, the fill in only applied to areas that have color (including transparency). In this case, the areas to fill include transparent areas and the colors within them.

Within the enclosed area, even partial areas that are part of the selection will be colored in, regardless of their color or anti-aliasing effect.

Transparent areas will only be filled in, in cases where closed areas are larger than the transparent areas like in ⑩.


[5] Make original sub tool

“Closed area fill” not only fills unfiled areas, but it is also able to fill in several distant closed areas at once.

However, “Enclose and fill” and “Paint unfilled area” have the same operation as the [Lasso] tool and the [Pen] tool, and therefore they are not perfect for filling large areas.

If you wish to enclose areas in other ways, try making a new sub tool.


① Select [Create custom sub tool] from the menu that shows after clicking the menu button from the [Sub Tool] palette.


② Select [Input process] and press [OK] after selecting [Closed area fill] for the “Output process” from the [Create custom sub tool] dialog box. Here, the [Figure] tool has been selected.


③ Since the created sub tool will appear in the [Sub Tool] palette, configure each item from the [Tool Property] palette and [Sub Tool Detail] palette.


④ Once the configuration is completed, right click the sub tool created from the [Sub Tool] palette and change the setting back to default from [Save as default].

You can paint distant closed areas by enclosing them in a rectangle now.

Sub Tools created by using other “Input process” functions will be enclosed as follows.


  • ”Input process”→ [Continuous curve]


  • ”Input process”→ [Unit curve]



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