Tech bytes for tea?

Are lamposts sticking out of your head in a photo – or are tree branches growing out of the ears instead? Remove them using the Clone Tool in GIMP.

Yesterday, we looked at some camera settings that will help get from the camera the best quality photo for GIMP to work on. Today we return to GIMP to remove unwanted objects like overhead cables and background dustbins from a snapshot.

Pict 1: Clear vista of Mt Fuji (apart from those cables) from across Yamaguchi train station on a bright sunny day.

A common advice for photographers is to look out for objects sticking out from a subject’s head or ears when framing the shot. And then reposition the subject to avoid these shot-spoliers.

However, sometimes the space and angle available might make it impossible to do so. Other times, the photographer is so focused on the main subject that he doesn’t notice the lamp-post or tree branch in the background, or that bright green dirty dustbin to the side.

Pict 2: The cables have been "removed" by copying neighbouring pixels over the cables.

I took the photo of Mt Fuji on a sunny day in early autumn. The view of the mountain was perfect apart from those darn electric cables stretching right across the frame. I wanted to include the train rolling into the train station at the small lake-town of Yamaguchi, as well as buildings at the foothills of Fujisan.

Let’s use the Clone Tool in GIMP to remove those cables (see Pictures 1 and 2).

Selecting the Clone Tool

Pict 3: Select the Clone Tool by clicking on its icon in GIMP's Toolbox

The Clone Tool allows you to paint over the cables by copying pixels from other parts of the photo. Select the Clone Tool from the Toolbox (see Picture 3).

In the tool options in the lower half of the Toolbox, select the “Fuzzy Circle” brush. You can do this by clicking on the square icon beside the Brush label, and selecting, from the drop-down panel of brush shapes, the circular brush with blurred edges (see Picture 4).

Pict 4: Choose the "Fuzzy Circle" brush from the dropdown panel in the tool options below the Toolbox

Drag the “Scale” slider in the tool options to control the size of the brush, or simply press the straight bracket keys on the keyboard – “]” to increase the brush size and “[“ to decrease. The cursor shows how big the brush is.

Cloning over the cables

To remove the cables near the centre of the Fuji photo, first designate the area from which to copy pixels from.

Hold down the Ctrl key and click on an area close to where you want to start painting over the cable. A circle with a cross-hair is displayed to indicate where this clone source is.

Pict 5: After designating the clone source, paint over the cables to copy pixels from the clone source.

Drag the cursor over the cable to paint over it (see Picture 5). As you paint over the cable, the clone source will also move such that it maintains its relative position to the cursor. If you make a mistake, press Ctrl-Z to undo and try again.

Change the clone source as you paint on different parts of the cables because the background behind the cable changes over the stretch of the cables.

Using a blurred edge for the brush helps merge the copied pixels seamlessly with the cable’s background. To make the merging even more seamless, reduce the opacity of the brush (drag the slider in the tool options) and paint a few times over each stretch of the cable.

Zoom in for the details

To work on areas where there are intricate details in the background behind the cables, get a bigger and clearer view by pressing the “+” key on the keyboard to zoom into the photo. For example, where the cables cross some pylons in the foothills and where the background of the cables change from sky to mountain.

Because of the clear edges involved, click the checkbox for “Hard edge” in the tool options. This allows parts of the pylon and the edge between the mountain and the sky to be copied crisply over the cables.

Reduce the size of the brush for more precision and use Ctrl-Z to undo mistakes. With some practice, you should get the hang of it quickly enough.

Cropping out the foreground

As you can see, cloning can be time consuming and straining to the eyes. If the unwanted objects or blemishes are around the edges of the photo, it is easier to just crop them out using the crop tool.

Pict 6: Cropping out the car park and other wires in the foreground also framed the photo more tightly drawing the focus to the mountain itself.

In the photo of Mt Fuji, I removed the car park and other wires in the foreground simply by cropping them out (see Picture 6).

Apart from unwanted objects in the photo, the Clone Tool can also be used to remove dark blotches in the photo arising dust or dirt spots on the lens or camera sensor.

Tomorrow, we’ll use GIMP to sharpen photos before sending them for printout.

Let’s go back to basics and see what settings on the digital camera will produce as good a photo as possible for GIMP to start working with.

New to digital cameras? Here are some basic settings to get the most out of your camera.

Yesterday, we used GIMP to turn a colour photo into black-and-white, and tinted it with another colour like sepia. Today, we give GIMP a break and go back to basics. I’ll share what camera presets to use in the digital camera to get the best quality photo from the camera – for GIMP to work on.

Having seen what photo-editors like GIMP can do to correct photographic mistakes and enhance snapshots, one may to tempted to become slipshod when taking photos.

After all, GIMP can straighten a crooked photo, crop a poor composition, remove unpleasant colour casts, and darken or brighten an overexposed or underexposed photo.

Later on in the series, we’ll see GIMP sharpening slightly blurred photos and removing lampposts sprouting from the top of people’s heads.

What a photo-editor CANNOT do

However, there IS a limit to what photo-editors can do. As they say, “Garbage in – Garbage out”.

Pict 2: Le'ts examine areas of this photo taken at the Kitano Tenmangu temple in Kyoto.

Even the best photo-editor cannot add in lost details from an overly blurred snapshot, or bring back image quality destroyed by an overly high JPEG compression. The JPEG compression throws image detail away and introduces unsightly colour blobs called image artifacts into the photo.

Neither can GIMP bring back details that were not captured in an overly overexposed or underexposed photo – such as the backlit silhouette of a person against a bright background.

It is also difficult to remove colour noise introduced by a high ISO setting.

Here are some basic camera settings I propound whenever somebody asks me what settings to use for their new digital camera. If you already know these stuff – please bear with me.

Use the maximum camera resolution

Digital cameras allow photos to be taken at lower resolutions. For example, you can set a 12 megapixel camera to capture photos at eight, three or fewer megapixels. This is for photographers who simply want to send the photo via email or share it online and want to upload the photo fast, or who are running out of space on their memory cards.

Pict 3: Using the maximum resolution means that even if you crop a small portion of the photo or enlarges it, there are enough pixels for a sharp print.

Pict 4: Taken at smaller sizes, enlarging the photo or cropping a small portion of the photo can lead to poor quality due to pixellation.

Unfortunately, the camera simply throws away image pixels and under-utilises the high resolution camera sensor that you paid your moolah for.If you want a good quality print to hang on the wall, use the maximum resolution of the camera. This gives GIMP more pixels to work with when tweaking the photo later on and a sharper photo if the print size is big.

It also allows you to crop a small portion of the photo and still have enough pixels for a good print. Should you need to email or share a photo online, you can still resize the photo to a lower resolution using GIMP.

Use the best quality setting

Most digital cameras store photos as JPEG files. You can specify how much compression to use. High compression results in smaller files but also means poor quality.

Pict 5: Using a low JPEG compression takes up more memory space but results in good image quality.

Pict 6: Using a high JPEG compression takes up less memory space but results in poor image quality.

Always choose the best quality setting so that a low compression level is used. After all, memory cards are cheap nowadays. There is no point forking out so much money for the camera and the vacation only to have the photos spoiled by a high JPEG compression setting.

Turn digital zooming off

Many digital cameras boast the “digital zoom” feature. Disable this feature. During digital zooming, the camera adds image pixels to the photo to make it appear bigger. This reduces the sharpness and quality of the photo.

If the subject really needs to be magnified, use GIMP to upsize the photo. A photo-editor on a computer can do a much better job than the data processor on board the camera.

Low light photography

Low light photography can produce some of the most challenging snapshots to correct. A high ISO introduces colour noise that is difficult to remove even in a photo-editor. A long exposure results in blurring due to camera shake. While the use of flash can result in harsh hotspots from reflections off oily skin.

For still subjects in low light, use a tripod along with a long exposure and low ISO. The low ISO minimises noise and the tripod removes blurring due to camera shake. The long exposure can result in some grainy noise but it’s not as bad as that introduced by a high ISO setting. However, if the subject is moving, the long exposure will result in motion blur.

Tomorrow, we’ll go back to using GIMP to remove overhead cables, branches sprouting from people’s ears and dustbins in the background.

Have you ever shot photos where the women look like they’re from Venus or the men look like they’re from Mars? Wrong white balance settings on the camera can lead to colour casts that coat everything in the photo with a hideous tinge. Use GIMP to remove these undesirable colour casts.

Yesterday, we used Layers and Layer Modes to tweak the brightness and contrast of photots. Today, we remove (or add) colour casts using GIMP.

Colour casts in photos are caused by the surrounding light at the time the shot was taken. Some casts makes a photo look nicer while others add ugly tints that make people in those photos look like the Na’vi from Pandora.

Pict 1: This stunning golden sunset was taken off the coast of Lake Biwa from the top of Hikone Castle in Japan.

Pict 2: The orange colour cast has been removed to restore the "original" colours - but the sunset has lost its soul.

White Balance setting on cameras

Before snapping a photo, set the camera’s White Balance setting to Auto (see Picture 3). Under most lighting conditions, the camera will automatically detect and remove colour casts from the photo.

Pict 3: Set the White Balance on the camera to Auto

To help the camera better judge the compensation needed, a photographer can change the camera’s White Balance setting from Auto to Sunlight, Cloudy or Fluorescent, for example, depending on the ambient lighting.

Be careful though – a common reason for unwanted colour casts in photos is when the white balance has been set wrongly. For example, you may have just shot outdoors in the sun using the “Daylight” white balance setting, and then move indoors to shoot under fluorescent lighting. If you forget to switch the white balance setting in the camera from “Daylight” to “Fluorescent”, the indoor shots will turn out with a strong blue or green tint.

Removing colour casts

In GIMP, apply Colors > Auto > White Balance from the main menu. This should automatically remove colour casts from most photos. Usually, the brightness and contrast are enhanced as well. To make the colours look richer, apply Colors > Auto > Color Enhance to make the colours more saturated.

Pict 4: Adjust the three sliders in the Color Balance dialog box until the colour cast has been eliminated.

If the above auto-adjustments do not remove colour casts completely, try doing it manually using Colors > Color Balance instead. The Color Balance dialog box pops up containing three sliders for controlling colour in the photo (see Picture 4).

The three sliders comprises pairs of colours on opposite ends of each slider. Moving a slider towards the colour on one end will increase the intensity of that colour in the photo and reduce the intensity of the colour on the other end of the slider.

For example, if there is a cyan colour cast in the photo, drag the cyan-red slider towards the red end to reduce cyan in the photo and make the photo look redder.

Above the sliders, there is a group of three radio buttons to specify whether the colour adjustments are applied to the Shadows, Midtones or the Highlights. Start with the Highlights before moving on to the other two ranges.

Pict 5: A beautiful sunset off the coast of Lake Biwa is marred by a cyan cast.

Pict 6: The cyan colour cast has been removed but the sunset still looks flat.

Pict 7: A red and yellow colour cast has been deliberately added to better convey the original warmth and glow of the sunset.

You can even add your own colour casts deliberately to add some atmosphere to the photo (see Picture 7).To compare the photo before and after the adjustments, toggle the Preview checkbox on and off.

At the bottom of the dialog box, there are three buttons to either Reset the sliders, Cancel the adjustments, or press OK to apply the adjustments.

Tomorrow, we’ll look at how to remove colour totally to turn photos into black and white, tint them a nostalgic sepia, or any other colour that strikes your fancy.

Pict 1: The Layers dialog in GIMP displays the layers in the image file and facilitates the manipulation of the layers.

Yesterday, we used GIMP’s automated adjustment tools to tweak the brightness and contrast of digital photos. We also tried out manual exposure adjustment using the Brightness-Contrast command. Today, we take a look at Layers and use Layer Modes as an alternative way of tweaking brightness and contrast.

Quick intro to Layers

When a digital photo file is opened in GIMP, it is placed in the Background layer. You can see the Background layer in the Layers dialog (see Picture 1). If you do any painting or make any brightness or contrast adjustments to the photo, pixels from the photo itself in the Background layer is altered permanently (unless you use the Undo command).

Pict 2: Layers dialog with duplicated layer. The Layer Mode and Opacity slider is at the top.

You can create additional image layers above the Background layer. The commands for manipulating layers can be found in the Layers dialog. The six icons at the bottom of the Layers dialog include commands to create a new layer, and to duplicate or delete a selected layer.

Inside the Layers dialog, click on a layer’s name to select the layer, double-click the name to rename it and toggle the eye icon to the left of the layer name to hide or show the layer’s contents. When a layer is selected, any painting or adjustments will be confined to the pixels in the selected layer.

Pict 3: The screen layer mode lightens the pixels below. Duplicate the layer twice for a stronger lightening effect.

The pixels in different layers interact with each other in different ways – depending on the Layer Mode for each layer. There is a total of 21 different Layer Modes. Select one using the “Mode” dropdown box right at the top of the Layers dialog.

The default mode for a layer is “Normal” – the pixels in the upper layer simply obscure the pixels in the layers below. Below the “Mode” dropdown box is the “Opacity” slider which determines how much of pixels in the layer are visible.

Below, we will use the three most commonly used Layer Modes to darken, brighten or increase the contrast of a photo.

Pict 4: Create a new layer from all the earlier layers and apply Contrast layer mode.

First duplicate the Background layer containing the photo by selecting the Layer > Duplicate Layer command from the main menu. You can also click fourth icon from the left at the bottom of the Layers dialog.

A new duplicated layer containing a duplicate copy of the photo is created above the Background layer. In the Layers dialog, click on the name of the duplicated layer to select it. Now click the “Mode” dropdown box at the top of the Layers dialog to change the Layer Mode of the duplicated layer.

To darken overexposed photos that are too bright, set the Layer Mode of the duplicated layer to “Multiply”. The photo is now darkened. If the darkening effect is too strong, reduce the opacity of the duplicated layer by dragging the Opacity slider (just below the “Mode” dropdown box) to the left (see Picture 2 above).

Pict 5: This photo was shot near the asylum in Saint-Rémy-de-Provence, France; where Vincent van Gogh stayed and convalesced for a year

Pict 6: The original overexposed photo has been darkened by duplicating the layer and setting its layer mode to "Multiply"

Making underexposed photos lighter

To lighten underexposed photos that are too dark, duplicate the background layer containing the photo and set the Layer Mode of the duplicated copy on top to “Screen”. As before, control the intensity of the lightening either by reducing the opacity of the duplicated layer, or by further duplicating the duplicated layer – or a combination of both (see Picture 3 above).

Pict 7: These beautiful roses in the courtyard of Monastère St. Paul-de-Mausole are underexposed and too dark.

Pict 8: The roses have been brightened up by applying the "Screen" layer mode to the two duplicated layers.

If the background layer containing the photo is the only layer in the Layers dialog, duplicate the background layer using the Layer > Duplicate Layer command and set the Layer Mode of the duplicated copy on top to “Overlay”. This will increase the contrast of the photo.

Pict 9: This photo of a forgotten statue at a corner of the asylum appears dull and flat.

Pict 10: An "Overlay" layer mode was used to increase the contrast of the statue.

Set the Layer Mode of the new layer on top to “Overlay” to increase the contrast (see Picture 4 above).

Tomorrow, we’ll look at how to remove unwanted colour casts from photos using GIMP.

Pict 1: These beautiful window paintings were on a wall right beside the Papal Palace in Avignon - France. The sides of the paintings taper inwards because of the steep upwards angle from which I snapped the shot.

Correct the distortion in perspective that is common when taking snapshots of tall buildings. Crop a photo to exclude distractions, or to change the composition of the photo.

Yesterday, we got ourselves oriented to the user-interface of GIMP, and tried our hand at straightening a crooked photo. Today we continue with common but simple photo-editing tasks like perspective correction and cropping.

Correcting perspective distortion

When taking photos of a tall building from an oblique angle, or while standing near it, the top of the building tends to taper inwards towards the top (see Picture 1). This distortion is called converging verticals and makes the building look as if it is falling backwards.

Pict 2: Distortion in perspective corrected using GIMP

To minimise such distortions, you can either go as far away as possible from the building (unfortunately you usually don’t get such luxury of space) and try to snap the building flat-on, or invest in an expensive camera accessory called a tilt-shift lens.

In GIMP, you can correct such distortions in perspective easily and for free – simply use the Perspective tool (see Picture 2).

Select the Perspective tool from the Toolbox (see Picture 3). In the settings section in the lower half of the Toolbox, select the following options: Corrective (Backward) radio button for Direction, and “Image + Grid” from the dropdown box for Preview.

Pict 3: Pick the Perspective Tool from the Toolbox

Pict 4: Drag the gridlines until the vertical and horizontal gridlines are aligned with the horizontal and vertical edges in the photo.

Click on the photo. A grid is overlaid onto the photo and a Perspective dialog box appears (ignore it for the moment). Drag the mouse within the grid to distort the gridlines.

Distort the grid until the vertical gridlines are aligned with the sides of the building walls, and the horizontal gridlines are aligned with the horizon and rooflines in the photo (see Picture 4).

Click the Transform button in the dialog box and the distortion is corrected.

Cropping

After using the Rotate or Perspective tool on the photo, empty areas are added around the corners that need to be cropped away. Cropping is also done to remove distractions from the surrounding and fill the frame with the main subject.

Pict 5: Highlight the area in the photo to be retained by dragging with the Crop Tool.

It is also done to adjust the aspect ratio say, from 4:3 to 3:2, or to crop a flat landscape-oriented photo into a tall portrait-oriented one. Many times, the photographer may simply want to enhance the composition of the photo by improving on the original framing of the photo.

Select the Crop tool from the Toolbox. Drag a rectangular selection around the area to be retained in the photo (see Picture 5).

A rough selection is good enough because the crop selection can be adjusted easily.

Pict 6: The photo was cropped to zero into two of the paintings.

Mouse over the side or corner of the selection and the cursor changes to include arrows that show which direction the selection can be adjusted. Click and drag these adjustment handles to adjust the crop selection inwards or out.

To move the position of the crop selection itself (without altering its size and shape), move the mouse over the centre of the selection and drag it to its new location within the photo.

Once you are happy with the crop selection, press Enter on the keyboard to crop the photo (see Picture 6).

Tomorrow, we’ll look at how to make simple exposure adjustments to darken or brighten an overexposed or underexposed photo.