Roselith Color Plates

Take an image to four color plates.

Roselith is an offline iPhone and iPad workbench for mathematical CMYK separation and round-dot screening studies. Import your own PNG or JPEG, adjust individual plates and export useful files. All current tools are included in one purchase.

FOUR PLATES IN VIEW Inspect cyan, magenta, yellow and black positives together. Select a plate to adjust its screen angle, ink density and tone gamma. Adjust common black share in Proof. Undo and redo retain 20 settings changes. Eight named presets can retain your ink and output settings.

STUDY THE OVERLAP View a digital screened composite and toggle individual inks. Visibility changes the composite only; all four positive plates still export. Original City terraces, Orchard dusk and Color steps studies are optional starting points made for this app. A normal library starts empty.

REAL FILES FOR THE WORKBENCH Build eight files: a five-page PDF with four aligned plate pages and a composite/settings page; four opaque black-positive PNGs; composite PNG; settings CSV; and editable Roselith JSON. PDF plates share common corner registration targets and a 100 mm reference line. Preview the actual PDF, share files or save through the system sheet. Exported settings include measured raster coverage and actual size.

CHOOSE THE OUTPUT Request 40–160 mm width, 150 or 300 DPI and 12–50 lines per inch. Actual size is reduced when needed to fit 180 × 220 mm or the 2000-pixel-per-axis limit. Files shows exact physical and pixel dimensions. Choose A4 or US Letter PDF; print at 100% and measure the reference before use. High frequency at low DPI has few pixels per dot; use 300 DPI or lower frequency.

KEEP EDITABLE PROJECTS Keep up to 24 local projects. Search, reopen, rename, duplicate or delete. Import a JSON backup to restore the original image and settings as a new project. Make backups outside the app before deleting or uninstalling; there is no trash. Files import accepts PNG/JPEG up to 8 MiB and 24 megapixels; the normalized working image is up to 1600 pixels per axis. Transparent pixels flatten onto white. JSON import supports up to 16 MiB.

ON IPHONE AND IPAD The phone focuses on a four-plate wall and contextual controls. A wide iPad shows positives, composite and the selected-plate inspector together. Native typography, Files, sharing and PDF preview keep the workflow familiar.

PRIVATE, PURCHASED ONCE No account, subscription, in-app purchases, ads, tracking, analytics, SDK, backend or app network requests. Projects stay on the device. System backups, file providers and sharing follow your device settings.

SCOPE This is a standard RGB mathematical CMYK and round-dot digital study tool. It is not ICC separation, a calibrated color proof, press-certified output or a guaranteed print result. No spot-ink matching, underbase, exposure or mesh calculation, camera, cloud synchronization or moiré avoidance guarantee. Verify and calibrate your actual print with your own materials and process. Use content you own or may use.

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