Photo Collage Maker

Professional photographers and content creators often require a reliable method to combine multiple images into a single cohesive layout. This tool addresses the specific need for high-resolution composition without the privacy risks associated with server-side processing. When you upload photos to cloud-based editors, you often lose control over the source files or suffer from aggressive compression algorithms that degrade the visual fidelity. This local application solves that problem by utilizing the computing power of your own device.

Accuracy in pixel mapping is critical when preparing files for print or high-density displays. A miscalculation in the aspect ratio or a rounding error in the coordinate system can result in unwanted white lines (aliasing) between grid cells or blurry upscaling. By strictly adhering to integer-based coordinate logic and allowing user-defined dimensions, we ensure that the final output preserves the maximum possible clarity from the source material. The system supports complex grid definitions and handles masking operations dynamically.

The mathematical foundation involves calculating the optimal coverage of a target rectangle \( R \) by a source image \( S \). This requires computing the scaling factor \( k \) such that the resulting dimensions meet or exceed the target area while centering the content. This is often referred to as a "cover" fit in computer graphics. Furthermore, the application manages the z-index stacking implicitly through the drawing order, ensuring that borders and background fills render correctly behind the masked image layers.

When fitting an image into a grid cell, we calculate the aspect ratio \( R \) to determine whether to crop vertically or horizontally. The aspect ratio is defined as:

To perform a "Cover" fit (similar to CSS object-fit: cover), the scaling factor \( S \) is determined by comparing the image ratio \( R_{img} \) and the container cell ratio \( R_{cell} \):

The final export resolution \( N_{pixels} \) depends on the chosen canvas width \( W \) and height \( H \), typically set to maximize quality.