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7 Edit Images with Free Linux Tools

Image Editing is one of the most important areas where Linux programs excel over Windows programs. In this chapter, we will describe how to use the image editing tools in Libre Writer, Libre Draw, Gthumb and Pinta to replace MS Windows image editing programs. This chapter includes the following four sections:

7.1 How to Use the Libre Writer Image Editor
7.2 Create Transparent Images with Pinta
7.3 Editing Images with Libre Draw
7.4 Resize and Crop Images with Gthumb.  
Gthumb is a free image editing tool that comes with Linux Mint. We will use it primarily to precisely resize and crop images. There is no need to install it from the Mint Software Manager. Instead, click on Menu, Graphics, Gthumb to select it. Then right click and select Add to Panel.

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This will put the Gthumb Quick Launch Icon in the bottom panel. Right click on the icon and click Move. Then move it to the left hidden panel.

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Gthumb will display a bunch of recently used images. First, we want to select the image we want to resize. Then click on Resize which is in the right side menu near the bottom of the list.

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This image is currently 624 pixels wide by 374 pixels high. Click on the drop down arrow to change the Dimensions from Percent to Pixels.

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Then click on the Minus sign to lower the width to 460 pixels.

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This will automatically lower the Height to 276 pixels. We next need to crop 3 pixels off the top and bottom to get the height down to 270 pixels. Click File Save. Then click on the Crop which is in the right menu just below Resize.

One of the most popular and most expensive Windows programs for editing images pixel by pixel is Adobe Photoshop. There is a similar program for Linux called GIMP. Both of these programs are extremely complex. Pinta is a free simple image editor that is much easier to learn and does nearly as good of a job as GIMP or Photoshop. In this article, we will explain how to turn this image into a transparent image and then clean it up pixel by pixel:

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Note that if you copied and pasted a regular JPG image into a Libre Draw document with a gradient page background, the JPG image will show with a white background. To change this background from white to transparent, download Pinta from the Mint software center. Then open it. Then navigate to the image we want to edit and open it.

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In the left side menu, just below the word palette, click on the black box to open it.

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Place your cursor over the Transparency button and slide it all the way to the left. Then click OK. This will change the “primary” color to transparent. Then click on the Paint Bucket in the left side menu.

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This will bring up the Tolerance Slider. Slide it to the right to set it for 20. Then set the cursor in the white area of the image and left click it to turn the white area into transparent (checkered area).

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Most of the background is not transparent. However, there is a small area under the bottom front of the laptop that is not yet transparent. Click on the plus magnifying glass to the right of 100% to make the image bigger. Click the plus magnifier three or four times until the box is set for 400%. This will make it easier to see the part of the background that is not yet transparent.

Some functions require that all of our images be at the exact same width and height. While some programs come with automatic image “resizers” others do not. If we have the wrong size image, it will just display badly. Online slideshows are one example of a function where all of the images in the slideshow need to be the same height and width. Another example is Facebook images. These are special images we assign to our website pages such that when the website page is shared on Facebook, the special image displays above the title of the article or page being shared. Facebook has all kinds of hidden rules to determine how this image will be displayed. For example, any image with a dimension under 200 pixels will not be displayed at all. Large or odd shaped images will be cropped such that only part of the image is displayed. This makes it look like we do not know what we are doing when in fact it is Facebook which has failed to provide the automatic resizing tools.

After years of trial and error, we have determined that an image that is 460 pixels wide by 270 pixels wide is most likely to be displayed correctly on Facebook. We will use Libre Draw to create this special image and then use Fotoxx to set the specific dimensions for this image. In our last article, we created the following Libre Draw document with three transparent images on a gradient background.

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First to set a ratio that is about 460 by 270, we need to display the Libre Draw Gridlines. Click on View, Grid, Display Grid.

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This will place a series of thin gray lines to form boxes in the Libre Draw background. To make the space we need easier to see, click on a rectangular box in the bottom drawing tool bar and set it to take up the grid leaving two rows on the top and both sides and three rows on the bottom. Right click on this square and click area. Set the Color for None.

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Then right click on the rectangle again and select Line. Then set the line color for blue and the line thickness for .10 inches.

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Here is what our rectangle now looks like with the grid lines in the background.

While MS Office 2003, 2007 and 2010 cost a small fortune, at least they came with a basic image editing tool called Office Picture Manager. Picture Manager could be used to crop, rotate and resize.

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Sadly, in a cost saving move, MS Office 2013 abandoned Office Picture Manager (which had seen no real changes since 2003). There are some image editing tools in MS Word. But basically MS Office 2013 and MS Office 2016 do a terrible job of editing images. We will therefore describe how to use several free Linux tools and a series of steps to edit images.

These steps and tools include:
#1 Capture Screen Images with Shutter
#2 Compress Images with Libre Writer
#3 Edit images with Libre Writer
#4 Save images with Libre Writer
#5 Create Transparent Images and Edit Pixels with Pinta
#6 Create and Edit Images with Libre Draw
#7 Precisely Resize Crop and Rename Images with Gthumb

We have previously explained how to use Shutter. Here we will look at how to compress, save and edit images with Libre Writer. Then in our next article, we will look at how to create transparencies and edit pixels with a free Linux tool called Pinta which is available in the Mint Software Manager. To illustrate these seven steps we will look at how we created the following image:

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#1 Capture Screen Images with Shutter
To create this image, we went to the Acer website and copied the following image of an Acer C910 laptop.

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We also downloaded the acer logo and the Linux Mint Logo.

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#2 Compress Images with Libre Writer
After capturing an image with shutter and pasting it into a Writer document, we want to left click the image to select it. Then right click the image and select compress to reduce the file size.