Image resolution, dimensions and file size explained
Understand pixels, print density and encoded bytes before resizing.
Reviewed by HSQ Tools ·
Dimensions count pixels
A 2400 × 1600 image contains 3.84 million pixels. Reducing it to 1200 × 800 leaves 960,000 pixels, one quarter as many. This arithmetic does not mean the encoded file becomes one quarter of its original bytes.
Aspect ratio describes shape: both examples are 3:2. If you resize to 1200 × 1200 without cropping, the image stretches. Crop to the desired shape first or preserve the ratio while setting dimensions.
Print density changes physical size
At 300 pixels per inch, 2400 × 1600 pixels correspond to about 8 × 5.33 inches. The same pixels at 150 pixels per inch correspond to about 16 × 10.67 inches. Changing a density tag alone adds no detail.
HSQ’s resizer works with width and height in pixels. It is not a print-preflight system and does not promise color-profile preservation. Enlarging an image interpolates new pixels rather than recovering camera detail.
Bytes depend on the content and encoder
An almost flat illustration and a detailed photograph with the same dimensions can encode to different file sizes. Alpha, compression mode and image metadata also affect bytes. Measure the downloaded file when a website sets an upload limit.
The resizer uses staged Lanczos reduction and applies sharpening and contrast adjustments. Inspect fine text and edges for halos before publishing. If the dimensions are already right, try compression instead; if the format is wrong for the destination, conversion is a separate step. Always preserve the original.
Diagnose the requirement you actually missed
Separate the destination’s requirements into shape, pixel dimensions and maximum bytes. A square 1000-by-1000 image can satisfy a pixel rule and still exceed a byte limit; a tiny JPG can satisfy the byte limit and still be too narrow.
If a print preview reports low resolution, calculate available pixels divided by physical inches. If a website rejects the file, read the upload error and check its format and dimensions. Changing a DPI tag will not fix an incorrect aspect ratio or restore lost detail.