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Inspect any image down to the exact source pixel.
Coordinate Preview is a lightweight, native macOS image viewer for designers, developers, and QA workflows. Hover over an image to read its original pixel coordinates, inspect a nearest-neighbor magnified sample, and navigate large or long images without losing context.
- Pixel-accurate coordinates — coordinates are calculated from the decoded source image after applying its EXIF orientation, independently of window size and Retina scaling.
- Built-in pixel loupe — crosshair guides, a nearest-neighbor preview, and a
yellow outline make the current pixel easy to identify. Choose
6×,8×,12×, or16×magnification; the default is12×. - Precise keyboard inspection — after hovering, use the arrow keys to move the selected point one source pixel at a time.
- Zoom and pan made for long images — use toolbar steps or continuous
trackpad pinch-to-zoom. The normal fit-relative range is
0.25×–20×, with additional levels generated automatically for very tall images. - Interactive minimap — when an image extends beyond the canvas, a minimap shows the visible region and supports click or drag navigation.
- Jump directly to a row — press
⌘L, enter an original-imageycoordinate, and the app centers that pixel row whenever possible. - Native macOS workflow — open images from the app, Finder, or drag and drop. Multiple files open in separate windows.
- Local and dependency-free — image decoding and inspection happen entirely on the Mac using AppKit, ImageIO, and Core Graphics.
- macOS 13.0 or later
- Xcode 16 or later, including its command-line tools, to build from source
Clone the repository and run the install script:
git clone https://github.com/alex0811/CoordinatePreview.git
cd CoordinatePreview
./scripts/build-and-install.shThe script builds the Release configuration, applies a local ad-hoc signature,
installs the latest app at ~/Applications/CoordinatePreview.app, and refreshes
its Finder “Open With” registration.
To make Coordinate Preview the default viewer for a file type, select an image in Finder, open Get Info, choose Coordinate Preview under Open with, and click Change All…. Future script runs replace the app at the same location, so the association remains stable. Stale Launch Services registrations for the same bundle identifier are removed, but app files in other locations are not.
Build and install a debug configuration with:
CONFIGURATION=Debug ./scripts/build-and-install.shYou can also open CoordinatePreview.xcodeproj in Xcode and run or archive the
shared CoordinatePreview scheme.
| Action | Control |
|---|---|
| Open image(s) | ⌘O, Finder “Open With”, or drag and drop |
| Inspect a pixel | Hover over the image |
| Move by one source pixel | Arrow keys after hovering |
| Zoom | Toolbar controls or two-finger pinch |
| Reset to fit | Click the current zoom value in the toolbar |
| Pan a zoomed image | Two-finger scroll; direction follows the macOS setting |
| Navigate with the minimap | Click the thumbnail or drag its yellow viewport |
Jump to an original y coordinate |
⌘L, enter a row, then press Return |
| Cancel coordinate entry | Esc |
| Change loupe magnification | 显示 (View) > 放大镜倍率 (Magnifier Scale) |
- The origin is the image's top-left pixel:
(0, 0). xincreases to the right;yincreases downward.- Coordinates refer to the decoded, EXIF-oriented source pixels—not display points—so resizing the window or using a Retina display does not change them.
- Guides and the loupe appear only while the selected point is inside the image.
- Jump-to-row keeps the most recently hovered
xcoordinate. If none exists, it uses the horizontal center of the currently visible image.
Run the geometry test suite:
swift testBuild the app from the command line without code signing:
xcodebuild -project CoordinatePreview.xcodeproj \
-scheme CoordinatePreview \
-configuration Debug \
-destination 'platform=macOS' \
-derivedDataPath /tmp/CoordinatePreviewDerivedData \
CODE_SIGNING_ALLOWED=NO buildCoordinatePreview/— the AppKit application and image interaction UICoordinatePreviewCore/— reusable coordinate and viewport geometryCoordinatePreviewCoreTests/— Swift Testing coverage for geometry behaviorscripts/build-and-install.sh— local build, signing, installation, and Finder registration
macOS Preview does not expose a third-party extension point for this kind of pointer-driven pixel inspection. Coordinate Preview is therefore a small, standalone viewer that can be registered as the default app for image files.
Coordinate Preview is available under the MIT License.