OpenRaster: what layered .ora files preserve
A detailed format reference covering retained layers, conversion warnings, unsupported features and a safe exchange workflow.
Applies to Photo 0.9.0 on photo.et.
OpenRaster is a layered exchange format, not a complete substitute for a Photo project. Browser saves download a copy.
What this reference covers#
PhotoCraft opens and saves OpenRaster (.ora), the layered format Krita, MyPaint, GIMP, Pinta and others share. Open and save use a shared format implementation, including in the browser. The browser build accepts .ora too. A file is recognised by its mimetype entry, so an OpenRaster file with another extension still opens as one.
Compatibility table#
| Content | Open | Save |
|---|---|---|
| Pixel layers (any size and position, also off-canvas) | yes | yes, cropped to their pixels |
| Groups, nested | yes | yes |
| Pass-through groups | isolation="auto" without a blend mode | isolation="auto" |
| Names, visibility, opacity | yes | yes |
| Blend modes | the svg:* names, svg:plus, and Krita's krita:* names | svg:* where the spec has the mode, else krita:* (read back by Krita, Normal elsewhere) |
| Locks | edit-locked, alpha-preserve | the same |
| 8 and 16-bit | yes (the deepest layer sets the depth) | 8-bit documents as 8-bit PNGs, 16 and 32-bit as 16-bit PNGs |
| Resolution | xres | xres and yres |
| Merged image and thumbnail | not read (we render our own) | written (mergedimage.png, Thumbnails/thumbnail.png) |
Saving reports what OpenRaster can't hold, layer by layer: pixel masks are applied to the layer's pixels, fill opacity is folded into the pixels, text, shape, fill and smart object layers are written as their rendered pixels, and adjustment layers, layer styles, vector masks, clipping, alpha channels, metadata and a colour profile other than sRGB are left out. Xor and Paint.NET's Color Burn and Color Dodge variants have no OpenRaster name and are saved as Normal. CMYK, Lab and other modes are refused with a message to convert first; Grayscale saves as RGB.
An OpenRaster file is the document's own file only while it holds everything in it. When the document contains features that OpenRaster cannot preserve, File › Save does not simply save over the .ora: Save As opens on a PSD of the same name, with a notice listing what OpenRaster would drop. A save to an .ora path then writes a copy, as Photoshop does for formats that can't keep everything: the document keeps its file and its unsaved changes. In the browser, saving produces a download.
OpenRaster elements other than stack and layer (MyPaint's text, for example), missing layer images and unknown composite operations open with a warning instead of failing the file. Krita's W3C Soft Light (svg:soft-light, krita:soft_light_svg) and its own Hard Mix open as Photoshop's Soft Light and Hard Mix, which differ slightly, also with a warning.
Check the imported result#
- Keep the original file and open a copy with File → Open.
- Read warnings and compare the visible image with an export from the originating application.
- Inspect layer names, groups, visibility and blend modes, not just the flattened preview.
- Download an editable .pcraft working copy before experimenting with other export formats.
A successful open establishes that this file was readable. It does not guarantee support for every version of the originating application or every feature used by that format.
Continue reading
Sources and edition notes
Adapted for the browser edition from the pinned PhotoCraft 0.9.0 source. Upstream documentation may also describe desktop workflows.
- docs/ora.md — Adapted from the upstream documentation for this pinned release.
Try it in Photo
Save your work before leaving the editor. Review the editor overview for file formats and browser limitations.
Open Photo ↗