Tech bytes for tea?

The many selection tools in GIMP provide different ways to make and modify selections of people or objects in photos. The selected people or object can then be tweaked and adjusted without affecting pixels outside the selection. For example, the pixels within the selection could be darkened or lightened or the colour could be made more vivid.

Sometimes, none of the selection tools we’ve covered can quite select an object properly – parts that should be selected are not selected, while pixels that should NOT be selected are selected instead.

For example, in the photo of the youth working on his laptop, we want to isolate him from the mundane background and replace the background with something refreshing. But his outline is highly irregular and complicated so the Rectangle and Ellipse Select Tools are out – unless he is a rectangular or oval android.

Make a rough selection first using the Free Select Tool.

The Fuzzy Select, Select by Color, and Foreground Select Tools are also out of their depths here because there is not enough contrast between the youth and the colours making up the background.

In this case, we start by using one of the usual selection tools to make a rough first-cut selection first, and then modify and perfect the selection by entering the Quick Mask mode.

Here, I used the Free Select Tool to encircle the youth, his laptop and the table – including a small area just outside of the outline. You will see the “marching ants” indicating where the selection boundary is.

Entering the Quick Mask mode

Quick Mask mode overlays unselected areas with a translucent pink.

To enter Quick Mask mode, click on the Quick Mask icon (the small dashed rectangle icon at the bottom left corner of the image window), or press Shift-Q on the keyboard.

A translucent red tint is overlaid onto the photo showing the areas that are NOT selected.

This translucent pink overlay is called the selection mask. It works like masking tape in a physical paint job. You stick masking tape over areas where you don’t want the paint to get into, so that only the unmasked areas will be painted.

The selected areas – the youth, his laptop and the table – will be free from the red tint. Everything else that is not selected, like the grass, the chair and the wooden walls in the background are tinted temporarily with the translucent red.

Modifying and perfecting the Quick Mask

Do two things before going any further:

1. Press “D” on the keyboard to reset the colour swatches to black and white.
2. Activate the Paintbrush Tool in the Toolbox.

Zoom into the boundary area between the youth and the background to work on the details (“+” key to zoom in and Spacebar to pan). The default Foreground colour is black.

Reducing the selection

Paint on those areas on the photo that are NOT supposed to be selected but are selected – they are supposed to be overlaid by the translucent pink but are not.

As you paint, those areas will be overlaid with the translucent pink (although the Foreground colour is set to black) to indicate they have been unselected. Press the square bracket (“]” and “[“) keys to increase or decrease the size of the brush.

Adding to the selection

If you accidentally paint into the areas which is supposed to be selected, don’t worry. Click “X” on the keyboard to swap the colour swatches so that white is now the Foreground colour.

Paint on the quick mask until only the youth, his laptop and the table is not pink.

Paint over those areas that are supposed to be selected but are not – these areas are overlaid in translucent pink even though they are not supposed to be.

Instead of adding white, you will see the translucent pink erased from those areas painted, indicating that those areas are now selected.

In this way, finetune the mask, especially in the border region around the outlines, until only the youth is free from the translucent pink. Zoom in to inspect and work on the details.

You can switch between black and white for the Foreground colour by pressing X on the keyboard.

Confirming the selection

Check the marching ants selection boundary.

Press Shift-Q or the click on the Quick Mask icon to get out of Quick Mask mode. You will see the marching ants again indicating the selection boundaries.

The youth, his laptop and the table is now precisely selected while the background is not.

If you find the selection boundaries are still not perfect, enter Quick Mask mode again to modify the mask and get back out to check the selection boundaries. You can keep shuttling in and out of Quick Mask mode until the mask/selection is perfect.

Now any command you make within GIMP will apply only to the pixels within the selection.

Switching the background

Once you are happy with the selection, press Ctrl-C or Edit > Copy to put the selected pixels into the Clipboard.

Green fields and blue skies. Photo from morguefile.com

Open the new photo that will serve as the new background. Press Ctrl-V or Edit > Paste to paste the youth onto the new photo.

The pasted pixels will be added as a new temporary layer called “floating selection” that floats above all other layers in the image. In the Layers dialog, double-click the label of the floating layer type in a meaningful name and press Enter. The floating layer will be converted into a separate and permanent regular layer.

After: The refreshing green fields and blue sky matches the drink he is sipping.

Activating the Move Tool from the Toolbox, you can drag the pasted layer to re-position it to the right place. You may need to resize either the new background photo or the pasted layer in order to match the sizes.

The edge of the youth may look too sharp and artificial at the moment, but we’ll address that in tomorrow’s tutorial.

Pict 9: GIMP Text Editor

To edit the text in the title, click on it in the image window with the Text Tool. The Text Editor pops up again for you to edit the text.

Pict 1: Scrapbook cover/page

They share their photos online even while they’re still overseas on holiday, but nothing beats a physical coffee-table scrapbook for family and close friends to thumb through and pore over.

In the first half of this tutorial today, we’ll use a photo as a background for a scrapbook cover/page and bring in additional photos. We’ll resize them as thumbnails and position them on the page.

In the second half tomorrow, we’ll add text titles and captions, and add outlines to them, as well as the thumbnails.

Including additional photos as layers

Pict 2: Single Background layer when photo is first opened. This lonesome koyo was languishing on the grounds of the Ginkakuji in Kyoto.

When a photo file is first opened in GIMP, it resides on the single Background layer.

In our example, the photo file comprises the macro shot of the lone koyo (red maple leaf in Japanese) in the Background layer. We want to bring in two additional photos of koyo scenes as thumbnails.

Pict 3: Additional photos

Pict 4: Additional photos as layers

The two photos will be brought in as additional layers – one photo on each layer. For a quick introduction into layers and various ways of manipulating them, read Part 5 of the Basic GIMP series on “Correcting exposure using layers”.

You can see the different layers in the file inside the Layers dialog.

To reduce the size of the moat photo to a thumbnail, click on its name in the Layers dialog to select it and then use the Layer > Scale Layer command from the main menu. As a shortcut, simply right-click on the moat layer in the Layers dialog and select the Scale Layer command from the pop-up menu.

Pict 5: Scale layer down to thumbnail size

In the Scale Layer dialog box that pops up, I typed in 300 in the Width field. The Height field was automatically updated to 225 to keep the aspect ratio of the layer unchanged to avoid distortions. Both the default Interpolation setting of Cubic or Sinc (Lanczos3) will do the resizing with good quality.

Press the Scale button to complete the resizing.

Repeat the same process to resize the other photo into thumbnail size.

Pict 6: Move, Alignment and Text tools in the Toolbox

Positioning the thumbnails

To move and position the thumbnails, activate the Move Tool from the Toolbox. Now you can just click and drag any layer you see in the image window.

Pict 7: Options for the Alignment Tool

To align the two thumbnails, activate the Alignment Tool in the Toolbox. Click the first thumbnail and shift-click the second thumbnail to select both. You can also drag a rectangle that encloses both thumbnails to select both at the same time.

In the Tool Options, click one of the icons to align either the left or right edges of the thumbnails.

Tomorrow, we’ll add text captions and outlines to the elements in the scrapbook cover/page.

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.