modern-pdf-lib

---

modern-pdf-lib / computeImageDpi

Function: computeImageDpi()

computeImageDpi(imageWidth, imageHeight, displayWidth, displayHeight): ImageDpi

Defined in: src/assets/image/dpiAnalyze.ts:57

Compute the effective DPI of an image given its pixel dimensions and display dimensions in points.

PDF uses 72 points per inch, so:

DPI = imagePixels / (displayPoints / 72)

Parameters

imageWidth

number

Image width in pixels.

imageHeight

number

Image height in pixels.

displayWidth

number

Display width in PDF points (1/72 inch).

displayHeight

number

Display height in PDF points (1/72 inch).

Returns

ImageDpi

DPI information.

Example

import { computeImageDpi } from 'modern-pdf-lib';

// A 3000×2000 image displayed at 4.17×2.78 inches (300×200 points)
const dpi = computeImageDpi(3000, 2000, 300, 200);
console.log(dpi.effectiveDpi); // 720