Marginal Gains launches Suihei for Mac to straighten photos with per-image angle detection

MARGINAL GAINS INC. says its new macOS app Suihei levels each photo individually, crops out blank corners and keeps all processing on the user’s Mac. The app is aimed at photographers handling large sets of images and is available now on Apple Silicon Macs through the Mac App Store.

Why it matters: - Suihei targets a common bottleneck in photo delivery: straightening large batches after a shoot. - The app is designed to save time by handling tilt correction, cropping and review in one local workflow. - MARGINAL GAINS INC. says the software keeps source files untouched and does not upload photos anywhere.

What happened: - MARGINAL GAINS INC. introduced Suihei, a macOS app for leveling photos on Apple Silicon Macs. - The app estimates the tilt of each image separately, then corrects the full set in one pass. - The company says the app is available from the Mac App Store for Macs running macOS 26.4 or later. - The product page is available at product details.

The details: - Suihei crops each rotated image to the largest rectangle that fits inside the corrected frame, removing blank corners. - The workflow keeps the photographer in control. If the AI is uncertain, the app shows the angle as a live preview instead of applying it automatically. - Photographers can review results mostly from the keyboard and fine-tune any photo by hand. - Corrected copies are saved to a separate folder and keep EXIF metadata. - Uncorrected frames are copied byte for byte rather than recompressed. - All processing runs locally on the Mac, including the built-in AI, and works offline. - The built-in AI does not learn from a user’s photos or edits during use. - The App Store privacy label for Suihei reads "Data Not Collected." - The interface is available in 33 languages, including English, Japanese, German, French, Spanish, Chinese and Korean. - Arabic and Hebrew are laid out right to left. - Suihei works with JPEG, HEIC and PNG files.

Between the lines: - The product leans into privacy and control as differentiators, which may appeal to professionals who do not want cloud processing or automatic image generation. - The emphasis on per-image angle detection suggests the app is built for real-world shoots where camera tilt changes frame to frame. - The company also points to a working photographer’s client jobs as the basis for the workflow, which signals a production-focused design.

What's next: - Suihei is free to download, with the first 100 exported photos free and 10 more free each day after that. - Viewing and editing are never limited. - A one-time in-app purchase called "Unlock Export" removes the export limit permanently. - The purchase price is US$39.99, with regional pricing varying by App Store market. - The company says there is no subscription. - MARGINAL GAINS INC. also says it will continue developing its own macOS software alongside client work in mobile apps and business systems.

The bottom line: - Suihei packages tilt detection, cropping and local-only processing into a Mac tool built for photographers who need fast batch cleanup without sending images off-device.