The resize dialog will open. IDimager allows a so called “Proportional resize”. This resize method enables you to specify a size value for the longest side of the image. The shortest size will be calculated by the application. Proportional resizing is very handy when you need to resize landscape and portrait images combined. If you deselect the “Proportional resize” option you will be able to set a custom width and height value.
Optionally enter the resolution for the resulting images and select the units (pixels/inch or pixels/cm).
Now enter the size. The size can be specified in pixels, in inches, or centimeters. The number of pixels for the last two sizes will be calculated based on the resolution and size specified.
Use the Interpolation option to recalculate the pixels for downsizing or upsizing. Depending on the image’s content you may need to play with the different interpolation filters to see which filter works best for a particular image. As a rule of thumb, you can use Lanczos3 for downsizing and B-Spline for upsizing. Using an interpolation filter is optional and will slightly slow down the resize process.
The option “Enlarge images that are smaller” can be set to upscale images that are smaller than the size required for the resize. If de-selected, than smaller images will keep their original size.