This is the format of the geometry string. Any of the values may be omitted, depending on the context:
x +- +- {%@!<>}
This is the ImageMagick description of the geometry string:
By default, the width and height are maximum values. That is, the image is expanded or contracted to fit the width and height value while maintaining the aspect ratio of the image. Append an exclamation point to the geometry to force the image size to exactly the size you specify. For example, if you specify 640x480! the image width is set to 640 pixels and height to 480.
If only the width is specified, the width assumes the value and the height is chosen to maintain the aspect ratio of the image. Similarly, if only the height is specified (e.g., "x256"), the width is chosen to maintain the aspect ratio. To specify a percentage width or height instead, append %. The image size is multiplied by the width and height percentages to obtain the final image dimensions. To increase the size of an image, use a value greater than 100 (e.g. 125%). To decrease an image's size, use a percentage less than 100.
Use @ to specify the maximum area in pixels of an image.
Use > to change the dimensions of the image only if its width or height exceeds the geometry specification. < resizes the image only if both of its dimensions are less than the geometry specification. For example, if you specify '640x480>' and the image size is 256x256, the image size does not change. However, if the image is 512x512 or 1024x1024, it is resized to 480x480.
The x and y offsets, if present, can be preceeded with either a + or - sign. The + causes x and y to be measured from the left or top edges, respectively. Conversely, - measures from the right or bottom edges. Offsets are always measured in pixels.
Any method that accepts a geometry string will also accept a Geometry object.
Some RMagick methods interpret the geometry string values differently. Where this is the case the documentation for the method will explain the differences.
