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.
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.
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.
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.
Then click on the Minus sign to lower the width to 460 pixels.
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.
Click the Maximize button to make it the maximum size. Then click on the Height Minus button to reduce the Height to 270. This will crop 6 pixels off the bottom of the image. To reposition the cropping tool so that 3 pixels are taken off the bottom and the top of the image, click the plus sign to the right of Position three times.
Then click File Save As. Add the width and height to the end of the name of the image such as 3.4_460x270.jpg. Then click Save and OK. We now have an image that is exactly 460 pixels by 270 pixels to use as our Facebook Sharing image. Here is our final image.
This completes our chapter on editing images with free Linux tools. In the next chapter, we will look at how to use several other free Linux tools.