Image selections - Tutorial

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Working with image selections / masks

Learn how to use the various selection tools and apply filters to selected portion of an image only.

Narration transcript

Hello again, in this video I am going to talk about selections and image masks.

First, I'll copy a picture from a Firefox window and paste it into RealWorld Photos using the Image from clipboard wizard.

Switch to the "Simple select" tool using the toolbar button with popup menu. Click and drag to select a rectangle. The selected region is drawn normaly while the contrast of the rest of the picture is lowered. Click and drag again to select a different rectangle. Press ESC to cancel the selection. Try it once more.

When SHIFT key is down, the old selection is kept and a new rectangle is added to the selection. And a third one.

When the CTRL key is down, the new selection inverts the old one. Play with it to see how it works.

When both CTRL and SHIFT are pressed, the selections are subtracted.

Now, switch to the Rectangle select tool. It works similarly as the Simple select, but there are differences. When you release the mouse button, you'll control points and lines, just like with the ordinary rectangle tool, and you have all its features at your disposal. You can set corner radius or rotate the selected rectangle. Also, as you can see, the selection edge is smooth just like the rectangle edge would be and pixels can be partially selected and partially not.

Just like with simple select, if I hold the SHIFT key, a new region is added to selection. Similarly with the CTRL key or with both. These keys work with all the selection tools.

Switch to Ellipse select and select a region consisting of 2 ellipses. Switch to Polygon select and add a triangle to the selection. Return to Ellipse select and remove a small circle from the selection. Now, you have a fishy selection. Congratulations.

Try using the colorize filter. As you can see in the preview window, it would only influence the selected region. The drop shadow filter uses the selected region as the region that casts shadows. And the Bevel filter takes the beveled shape from the selection.

Drawing with ordinary tools while a selection is active will only influence the selected region.

Anyway, switch to the Transformation tool to convert the normal selection to a floating selection. You can change the shape of the floating selection quite easily. You can also apply effects to it. Note that the effect only apply to the floating selection and you cannot see anything else in the preview. This is very different from working with non-floating selection (also known as image mask). Filters working with floating selections are allowed to resize them.

Let's switch to the Magic wand tool. This tool selects group of pixels having a similar color as the clicked pixel. There are several matching modes and a configurable tolerance. Click and drag to see live preview of the selected pixels. In multipoint mode you can click multiple pixels to all of them will be used as source points.

The last of the predefined selection tools is Brush selection. Let's switch to it now. I guess you can see how it works. Note that the edge of the selected region is smooth, because the used brush is blurry. When applying a filter its effect will be smoothly interpolated between 100% and 0% as you cna see.

There is a couple of predefined operations that work directly with the mask. You can for example store the mask for later use. And recall it back. You can load or save it to file. You can also blur it even more. The effects will be very subtle in this case. And you can also grow, shrink or invert it. It works nicely with for example the Fill filter.

I hope you have learned a bit about selections, floating selection and transformations in RealWorld image editors. Similar functions will be available also in future versions of the icon and cursor editors. This tutorial has not covered 100% of what is possible to do, so feel free to ask how to do other
things with selection in the comments section.

Thanks for watching.