GIMP: Rotation and Shearing (when you need it)

 

The GIMP (GNU Image Manipulation Program) Editor has many powerful tools available that can fix image imperfections and enhance those pictures.

 Recently, I took several hundred images for a small business, Irresistible Jewelry here in Harlingen. These pictures were edited so that they would be posted on the Facebook business page over the course of the year. While on this task, there were several objects that caught my attention, like the wall-decoration cross pictured above. The cross featured several illustrative panels which depict the Crucifixion of Jesus on Calvary. The cross actually isn't that large in itself, but the amount of detail that went into these small panels is nothing short than impressive! These images are the type that one would find in those illustrative Bibles, but scaled down greatly into these small panels. These panels don't looklike much from a distance, but a 16MP camera can catch a lot of detail. I took a few extra closeups of the cross, so I can let people online know the amount of effort that went into these panels. While editing the images to show the individual panels though, I did run across a problem. Some of the images didn't come out as expected, and needed enhancements performed in order to fix the flaws. Luckily, GIMP has the tools available to perform such task.

Panels 1 and 2 with no modifications or filters

As you might tell, there is a very obvious problem here. The image is at an slight angle. How do I fix this?

Rotation Tool icon located on the Toolbox window

After selecting the Rotation Tool, click on the image. A grid appears over the image with the Rotate window open. Click on the arrows that control the angle amount, and keep clicking them until the appearance looks correct, and then hit the "Rotate" button. You can also hit the Angle label and enter the angle value manually. After trying a few trials and errors, I settle for a value of 1.1 degrees. As usual, I apply manual color enhancements to the image. The Level Curves Tool is located in the "Colors" menu as "Curves...", while the Hue-Saturation Tool is located as "Hue-Saturation..." under the same menu.

The saturation level was changed by 10.

Final Image

Shearing Tool

This image has two issue with it. The first one is that the image is at an angle, like the previous one. Another noticeable issue is that the perspective is off as well. As with the first image, I apply the Rotation Tool and apply a 1.1 degree angle change. After this, I click of the Shear Tool in the Toolbox.

Shear Tool icon in the Toolbox

Using the Shear Tool, I changed the magnitude X angle by -5 degrees. When the image perspective looks correct, hit the "Shear" button to apply the changes. After this, I use the level curves and hue-saturation tools to apply color enhancements like I did in the previous image.

The Final Image

GIMP has many powerful tools in its arsenal for one to use. The important thing to realize is to know which tool is appropriate for a given job and how to use that tool. Once that can be mastered, than images can be fixed and enhanced in much greater detail. The way images were meant to be seen.