README

Small, dependency-free PHP helpers for the math around image upscaling:

scaled pixel dimensions, megapixels and aspect ratio
the smallest upscale factor (2x, 4x, 6x, or your own list) that reaches a target size
pixel requirements and maximum print size at a given DPI

The library only does arithmetic. It makes no network requests and does not read or write image files.

Install

composer require tancky/upscale-calculator

Requires PHP 8.1 or newer.

Usage

use Tancky\UpscaleCalculator\Dimensions;
use Tancky\UpscaleCalculator\UpscaleCalculator;

$photo = new Dimensions(1200, 1500);

$photo->megapixels();   // 1.8
$photo->aspectRatio();  // "4:5"
$photo->orientation();  // "portrait"
(string) $photo->scale(4);            // "4800x6000"
(string) $photo->fitWithin(600, 600); // "480x600"

$calculator = new UpscaleCalculator(); // supports 2x, 4x and 6x by default

// Which factor do I need for a 4K wallpaper?
$calculator->factorFor($photo, new Dimensions(3840, 2160)); // 4.0

// Which factor do I need for an 8x10 inch print at 300 DPI?
$calculator->pixelsForPrint(8, 10);          // 2400x3000
$calculator->factorForPrint($photo, 8, 10);  // 2.0

// How large can I print the original?
$calculator->printSize($photo);
// ['width_in' => 4.0, 'height_in' => 5.0, 'width_cm' => 10.16, 'height_cm' => 12.7]

factorFor() and factorForPrint() return 1.0 when the image is already large enough and null when none of the supported factors is enough.

Pass your own factors if your upscaler supports a different set:

$calculator = new UpscaleCalculator([2, 3, 8]);

Testing

composer install
composer test

About

Maintained by Tancky AI. The default factors match the 2x, 4x and 6x options of the Tancky AI Image Upscaler, where the same calculations decide which option an image needs.

License

MIT

tancky / upscale-calculator

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