Resize with the right dimensions in mind.
Image dimensions are usually measured in pixels: width × height. Choosing suitable dimensions helps an image fit its intended space, but changing the pixel count does not necessarily improve its visual detail. Understanding aspect ratio makes it easier to resize without stretching.
What pixel dimensions tell you
A 1600 × 1200 image contains 1600 pixels across and 1200 pixels down. Its pixel dimensions describe the image grid, not its file size. Two images with the same dimensions can have very different file sizes because their content and compression settings differ.
Keep the aspect ratio when you want the same shape
Aspect ratio is the relationship between width and height. A 4:3 image can be resized to 1200 × 900 while keeping the same shape. If you change only one dimension and stretch the other independently, circles may look oval and people or objects may appear distorted. Enable the aspect-ratio setting when you want to preserve the original proportions.
Downscaling and upscaling are different
Downscaling reduces the number of pixels and can help an image fit a smaller display or reduce its output size. Upscaling creates additional pixels by interpolation; it can make the image larger in dimensions, but it cannot recover details that were absent from the source. When possible, start with an image that is large enough for its intended display.
Choose dimensions for the destination
Consider the space where the image will appear. A small thumbnail does not need the same pixel dimensions as a full-width image. For print, pixel dimensions alone are not enough: the intended physical size and print resolution also matter. For web use, test the image in the actual layout to make sure text and important details remain clear.
Resize a copy, not your only original
PDFRemaster’s resize tool reports the source dimensions and lets you enter new width and height values. It exports a new file so the original remains available. Check the result at its intended display size before replacing or publishing the source.