Cropping involves taking a rectangular portion from the centre of the image and discarding the rest. It will always be necessary on a partially rotated image if you are to restore a rectangular shape and if you want to control what is to appear on a print.
Most digital cameras produce images with a width to height ratio 4:3. No standard size of paper matches this ratio, so prints will either have uneven borders or the edges of the image will be lost. You might also choose to display or print a non-standard standard size in order to cut distracting detail from the image, better frame the image or to adjust the composition by re-positioning some key feature.
To crop an image, select the Crop tool from the GIMP window. This changes the pointer to a cross-hair with scalpel.
With the tool selected, drag over the area of the image. As you begin to drag a dark mask appears over the image. Moving the pointer reveals the area of the image that is to remain. Once satisfied with the cropping, click in the centre of the clear area to confirm the action.
If you will wish to make minor adjustments to the initial area selected, move the pointer over the edges of the clear area to reveal blocks in the corners and along each edge of the image . Drag on these blocks to expand or reduce the selected area.
The selected area can be moved, without re-sizing it, by dragging within its centre. (The pointer changes to the conventional four-way arrow with scalpel).
If you are totally dissatisfied with the area you initially select then clicking over the masked area removes the mask and allows you to start again.
For very fine control of the area to be cropped use the various position and size fields in the Crop Tool Options in the bottom half of the GIMP window.
If preparing an images to for printing on a specific size of paper or display on a TV or computer screen then "Aspect Ratio" is crucial. To set an aspect ratio first check the "Fixed" option. and then select Aspect ratio from the drop-down list. Use the following settings as required:
|Standard Computer or TV Screen||4:3|
|Wide-screen TV or Computer||16:9|
|6" x 4" Paper||6:4 or 3:2|
|7" x 5" Paper||7:5|
Once "fixed", the clear area will retain its shape when dragging on the boxes at the edge of the clear area. (The small Portrait and Landscape buttons will switch the order of the ratio figures.)
1. It is quite possible, sometimes desirable, to alter an image from landscape to portrait orientation, to remove unwanted detail, as was being done with the image above.
2. Severe cropping of an image reduces the size of the image and this may have an impact of it's overall sharpness when printed as the resolution will be reduced.