How to modify images using drawing tools? April 7th 2005

This guide introduces the basic drawing tools available in RealWorld Icon Editor - pencil, lines, polylines, curves, rectangles, ellipses, text, and dropper. The drawing tools are used to modify both raster images and icons.

Tools for flood filling, moving and resizing rectangular regions, and creating projected shadows will be discussed in a follow-up article.

This guide is intended for people with basic knowledge about RealWorld Icon Editor. It is recommended to go through the application tutorials first.

Blending and rasterization modes

All basic drawing tools (except Dropper) take into account current Blending mode and current Rasterization mode.

Blending modes

The blending mode controls how is the new shape mixed with already existing image.

The first green stripe on the screenshot was drawn using the Paint Over mode. Because the current color was partially transparent, you can see the black pixels behind the green stripe.

Replace mode was used with the second stripe. The black pixels were completely replaced by the semitransparent green ones.

The last stripe employs the Paint Under mode. It works just like the Paint Over, but switches the foreground and background pixels. In our case the result is the same as if the green stripe was drawn first and the black rounded rectangle second. This mode can save you some time, for example when you need to put your image on opaque background - just draw a rectangle behind the image.

Points of interest:

• If your current color is completely opaque (alpha is 255), there is no difference between Paint Over and Replace modes.
• If your background is opaque, the Paint Under mode would appear to have no effect.
• If your current color is completely transparent (alpha is 0), all drawing occurs in Replace mode, because other modes would have no effect. This saves you time switching to the Replace mode manually when erasing pixels.

Rasterization modes

There are two rasterization modes: Smoothing and No smoothing. In the first mode, antialiasing is applied to smoothly blend edges of drawn objects. The second mode produces objects with jagged edges. Also, the drawing tools offer less options in No smoothing mode - you will not be able to set outline width or polyline join type.

Primary and secondary colors

If a tool requires single color, left mouse button uses primary color and right mouse button uses secondary color. In cases, where the tool requires two colors, using right mouse button swaps them.

Images without alpha and images with palette

The raster image editor integrated into RealWorld products is aimed at truecolor images with full alpha channel. When capabilities of currently edited image format are limited, the drawing tools are limited as well:

• If image lacks alpha channel, the Paint Under blending mode is useless.
• If image has only 1-bit alpha, outlines of shapes drawn on transparent background cannot be smoothed and very transparent shapes will not be visible at all.
• If image uses palette instead of direct color, the palette is calculated dynamically as you draw. The image is then dithered. Drawing in this mode may be slower.

Pencil tool

The pencil tool is very simple, it allows you to replace pixel colors. When in Paint Over mode and using semitransparent black or white color, you can darken or lighten individual pixels to finetune your icon.

Line tool

This tool allows you to draw lines and polylines with selected joins and caps and defined width. When in polyline mode, draw the initial line just like in single line mode, then click anywhere to continue the polyline. To finalize a polyline, right-click in the raster editor or click the Finish button on the properties panel. Until the polyline is finalized, you may change its properties or color and you may change the position of joins by dragging them with mouse.

Note: the control point size is one image pixel, you might need to zoom in to be able to see them.

Curve tool

This tool draws 3rd-degree approximation curve that passes through all specified points. Start the curve just like you would draw a line, drag from first point to second point. Then press mouse button at the desired third point and eventually move it and release it. Continue until you place all required points. You may change point position later by dragging it. Once you are happy with the shape, click the Finish button or right-click in raster editor window.

Note: the control point size is one image pixel, you might need to zoom in to be able to see them.

Ellipse tool

This tool allows you to draw filled ellipses and circles or their outlines. Select the type (filled, outline, filled with alternate color), outline width and draw the ellipse by dragging your mouse from one corned of a bounding rectangle to the opposite one.

Rectangle tool

Rectangle tool can draw filled rectangles, rectangle outlines, and rectangles filled with alternate color. Corners of rectangles are rounded if Radius property in properties panel is greater than 0.

Text tool

Type text into the large edit box in properties panel, then click in the raster editor to place the text. You may move your mouse while the mouse button is down to see how the text would fit into your image. Font properties are accessed by clicking the Select font... link in properties panel.

Dropper tool

Click on a pixel in raster image editor to transfer color of that pixel into primary (left click) or secondary color (right click).

If you are using one of the other tools described in this guide and holding down CRTL key, active tool is temporarily switched to Dropper.

Resources

• RealWorld Icon Editor home page.

Summary

Described drawing tools cover the basic needs expected from each raster image editor. They support ordinary and antialiased drawing quality, various blending modes as well as floating point parameters (for example line width of 2.5 pixels).

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