Why does a resized image look stretched or blurred?

Separate aspect ratio, pixel dimensions and file size.

Preserve proportions

A 1200 by 800 image resized to 600 pixels wide becomes 600 by 400 when the height is left blank. This preserves its aspect ratio.

Resizing is not cropping

If a banner requires 590 by 350 pixels, its ratio is 59:35. An image with a different ratio needs cropping in an editor before resizing if you want to avoid stretching. Entering both dimensions here stretches the image.

Enlarging has limits

Making a small image larger cannot recover detail that was not present. Work from the highest-quality original and avoid repeatedly enlarging a reduced copy.

Check file size separately

590 by 350 pixels does not guarantee a file below 1MB. Inspect the exported dimensions and then its KB or MB size. Use the compressor afterwards only if necessary.

Review the actual placement

Open the downloaded file and check text, faces and circles for distortion. Check how the receiving webpage fits or crops it; a correctly resized image can still be cropped by the page layout.