Tech bytes for tea?

In yesterday’s case, clicking on the blue sky around the temple in the photo selected all the blue pixels “connected” to the clicked pixel by other selected pixels.

Select by Color Tool

If, say there is a window in the temple showing a bit of blue sky through it, those blue pixels won’t be selected when the Fuzzy Select Tool is clicked outside the outline of the temple.

Similarly, if the cursor is clicked inside the window showing the blue, the blue sky around the temple won’t be selected.

To add such segregated areas to the main selection, hold down the Shift key on the keyboard and click on those areas with the Fuzzy Select Tool.

For more control, I tend to prefer using the Fuzzy Select Tool together with the Shift key.

But if there are many isolated areas to be selected, a more suitable tool is the Select by Color Tool.

The Select by Color Tool works exactly like the Fuzzy Select Tool except that pixels from the ENTIRE photo that are similar in colour to the clicked pixel are selected – whether contiguous or segregated.

Foreground Select Tool in the GIMP Toolbox

Again, the Threshold value determines how similar a pixel should be in order to be selected.

So if the temple had many windows showing blue skies, clicking a blue pixel in any one of the windows would select all the blues pixels in the sky.

Unfortunately, any of the tourists wearing blue will also have their blue clothes selected. That’s why I tend to prefer the Fuzzy Select Tool because it allows me to control exactly what I want to select.

Foreground Select Tool

Another selection tool that can occasionally work wonders is the Foreground Select Tool. It is used to select an object in a photo against a background, preferably with contrasting colours (see above Picture).

This wild flower looks a tad pale and dull on an overcast day.

The pink flower now stands out against the pale background.

Activate the Foreground Select Tool from the Toolbox.

The cursor turns into a lasso. Use the cursor to drag an outline outside but around the flower. For selecting the outline, the tool behaves like the Free Select Tool. Select close to the outline of the flower but do not stray inside the flower.

Various stages of using the Foreground Select Tool. Click each thumbnail to open enlarged photo.

Once the outline is complete, GIMP overlays the area outside the outline with a dark blue translucent mask, while the appearance of the flower and its immediate surrounding inside the outline remains unchanged.

The cursor now changes into a paintbrush. Paint inside the flower.

There is no need to paint the entire flower. If the flower contains different colours, try to paint over the different colours to tell GIMP they are part of the flower. Avoid painting outside the flower.

After the initial painting, the dark blue mask closes in so that only the flower remains visible. The clearly visible areas indicate the areas that will be selected. In this case, GIMP did a perfect job.

You can still modify the mask if the flower had not been perfectly masked.

In the Tool Options are two radio buttons that determines the effect of painting on the photo.

By default, the “Mark foreground” option is selected. If there are parts of the flower that are covered by the blue mask, paint on those areas to unmask them.

If there are areas outside the flower that are not masked in dark blue, select the “Mark background” option in the Tool Options and paint on those areas to mask them.

To work the details, zoom in and vary the brush size by dragging the slider in the Tool Options.

Once the mask has been finetuned so that only the flower is clear and the surroundings are masked by the translucent dark blue, press Enter on the keyboard to convert the mask into a selection.

You can now make the flower stand out by dialing up the vividness using Colors > Hue/Saturation command from the main menu.

Caution: While outlining the flower or painting to define the area to be included or excluded, Ctrl-Z or the Edit > Undo command does not work. To restart the selection process, select some other tool in the Toolbox and then select the Foreground Select Tool again.

In the Basic GIMP series, we used the rudimentary Rectangle and Ellipse Select tools to create simple selections in a photo.

What if we want to select an object in a photo that has an irregular outline? Check out the Free Select Tool.

As with the other selection tools in GIMP, the Free Select Tool can be found at the top of the Toolbox.

The red traffic cones and receding pedestrian are a tad distracting behind the postbox.

Toning down the background focuses the viewer's attention on the main subject.

This is usually done to bring put the emphasis on a main subject by toning down the background, especially if the background is brightly coloured or distracting.

It is also a popular technique to turn a mundane snapshot into something arty.

Download the Before photo and follow along.

Activate the Free Select Tool at the top of the Toolbox

Using the Free Select Tool

In the Toolbox, activate the Free Select Tool. Click (and let go of the mouse button) anywhere on the edge of the postbox. Move the cursor to the next point on the edge of the postbox and click again.

GIMP joins the two mouse clicks with a straight line to indicate the edge of the selection you are making. An anchor point is also created at each end of the edge to indicate where the mouse was clicked.

Around the corners of the postbox, the edges are rounded. Zoom in (press “+” on the keyboard) to get a better view to make a more precise selection.

Where the curved edge begins, click but hold down the mouse button and drag the cursor along the curved edge. You can see selection boundary trace around the curved edge.

At the end of of the curved edge, release the mouse button. To continue selecting straight edges, simply click at the next point.

Repeat the above techniques around the edge of the postbox until you are back to the starting point. This completes the selection process.

Along the way, if you click at the wrong place or make a botched tracing around a curved edge, press the Backspace key on the keyboard. GIMP will remove the previous anchor point and line segment. Press the Backspace key once to remove each previous anchor point and segment.

Decolourizing and adding the tint

Once the postbox has been selected, press Ctrl-I to invert the selection. Drain the colour from the selected surroundings and tint it a pale red by using the Colors > Colorize command from the main menu.

In the Colorize dialog box, set Hue to zero and Saturation to 15 by dragging the corresponding sliders.

Set the “Resize layers” dropdown box to “All layers”. Press the “Center” button to centre the photo.

Pict 5: New pixels have been added to the sides of the photo.

When you press the Resize button, additional pixels will be added either to both sides or to the top/bottom of the photo. Unlike the Scale Image command, the original pixels remain untouched.