Mac Resize Tool

Mac Resize Tool computes target image dimensions and prepares parameter sets for macOS asset pipelines. It is intended for designers, developers, and photographers who need consistent sizes across web, apps, and automation scripts. The tool supports single-image scenarios and can serve as a building block for batch workflows. Typical use includes generating web thumbnails from high‑resolution assets and producing retina-variant sizes for app icons.
Core inputs include source_path, source_width, source_height, target_width, target_height, maintain_aspect, upscale_allowed, format, quality, and output_path. The core outputs include final_width, final_height, mime_type, estimated_size_bytes, and a derived output_path. The tool applies simple, deterministic calculations so that the same inputs always yield identical outputs, enabling reproducible automation.
Algorithms: If both target dimensions are present and maintain_aspect is true, ratio = min(target_width/source_width, target_height/source_height); final_w = round(source_width * ratio); final_h = round(source_height * ratio). If only one target dimension provided, compute the other using the source aspect ratio. If upscale is disallowed and targets exceed source, clamp to source. If no targets provided, return an explicit input error. If inputs are missing, zero or negative values, or the format is unsupported, errors are returned with explicit codes. The outputs are suitable for downstream image tooling and scripting.