"DPI resize" option

[dma_k]

When resizing the canvas (transformation filter) it is nice to have "DPI resize" option (next to "px" and "%" radio buttons) with a drop-down presets list containing also page sizes (A4, A3, etc) and width/height input fields are in cm. The image DPI is used to calculate how image will fit the page. The result is the same as print preview with "Single - DPI".
Motivation for this function: when scanning images we stip the border to save space, but finally want to create PDF with natural page size with original image e.g. centred.