Choose a scope
Tap a scope’s title to change it or choose Off. Use an Add scope menu above the plots to fill an empty position. Up to four scope positions are available.
Install on your Mac
This release requires macOS 27 or later. You need DaVinci Resolve on a Mac, a recent web browser, and a shared local network. GTap is the Resolve effect that sends the picture to Ghetto Scopez. Nothing needs installing on your phone or tablet.
- Download and unzip the latest release. Keep the Ghetto Scopez folder somewhere you want to keep it.
- Double-click Install.command. If Resolve is open, quit it when the installer asks. Setup continues automatically.
- Enter your Mac password when asked. The installer installs Node.js if needed, prepares the host and installs GTap. No developer tools or commands are required. It then starts Ghetto Scopez and opens this guide.
- Open Resolve and add GTap. Follow the connection steps below. Later, double-click Start.command to start Ghetto Scopez again. Keep its Terminal window open while using the scopes. Press Control-C in it to stop.
Internet access is needed if Node.js is not already installed. If macOS blocks the downloaded installer, review the message in Privacy & Security.
The release includes a prebuilt GTap effect for Apple silicon and Intel Macs. The installer checks that your macOS version can run it. The effect is currently locally signed. Apple notarization is pending Apple’s reactivation of the dormant Apple Developer ID.
Update or remove
To update, quit Resolve, stop the old host, unzip the new release and double-click Install.command. Then reopen Resolve. Saved viewer settings stay in the browser when you use the same address.
To remove GTap, quit Resolve and delete /Library/OFX/Plugins/SignalLabTap.ofx.bundle. Stop the host before deleting the Ghetto Scopez folder.
Connect Resolve to your screen
- Open Resolve and add GTap. On the Colour page, find GTap in the Effects library and add it to a serial node.
- Put the node after the image conversion you want to measure. For display-referred scopes, place GTap after your output Colour Space Transform. Anything after GTap is not included. Resolve’s automatic colour-managed output transform can happen after the node graph.
Place GTap immediately after the node that converts the image to the display space. - Set GTap’s input colour space. Choose the BT.709 or BT.2020 primaries that match the RGB signal reaching the node. GTap does not convert the image or change its appearance.
- Open the viewer address. GTap’s panel shows the host status and scope address. Open that address in the browser on your other device, on the same network.
- Tap Start listening. Open Controls to find it, or tap Fullscreen to start listening automatically. Play or scrub a clip if there is no picture yet.
Choose the matching display space.
The scopes measure the image at GTap’s node. Choose the input declaration and level range to match that image.
Make the viewer yours
Choose a layout
Open Settings to change the arrangement. If all scopes are off, tap Choose layout in the middle of the screen. On a phone in portrait, a single scope or vertical stack gives each plot more room.
Open Controls
Tap Controls to reveal listening, trace and overlay controls. The popup fades after a short idle period; tap Controls again to reopen it.
Go fullscreen
Tap Fullscreen for more space. Availability depends on the browser.
Adjust the trace
Gain brings faint trace detail forward. Brightness changes how bright the trace looks. These controls change the display, not your grade. Colour and smoothing options let you choose the trace appearance.
Use pinch or the mouse wheel on supported plots to zoom. Use Reset to return to the starting view. Vectorscope magnification enlarges the trace while reference markings stay in place.
The host indicator tells you whether the viewer is connected. The frame status tells you whether fresh data is arriving. A paused image can stay on screen while you compare or grade it.
Know what you’re looking at
Waveform
Shows levels from the left to the right of your image. Higher marks mean higher signal levels. Choose a plain trace, source colours or false colours by level.
RGB parade
Shows red, green and blue levels side by side. Compare the channels to spot colour casts and differences in their high and low levels.
RGB histogram
Shows how many pixels sit at each channel level. Choose overlaid channels, separate channels or a single colour channel.
Vectorscopes
Show colour direction and strength. Marks near the centre are less colourful; marks farther out are more colourful. Choose the full image, highlights, midtones, shadows or a combined highs/mids/lows strip.
DoubleD
Shows colour balance across image levels in two related plots. Choose a vertical or horizontal orientation. Colour guides remain visible even with a plain trace; the neutral axis is optional.
3D colour cube
Shows the spread of RGB colours in a cube. Drag with a mouse or finger to rotate it, pinch or scroll to zoom, and use Reset to restore the view.
Saturation vs luma
Shows colour strength from left to right and encoded luma from bottom to top. Use it to see whether stronger colours sit in darker or brighter parts of the image.
Hue histogram
Shows which hue angles appear most often. Almost grey and very dark pixels are excluded because they do not give a useful hue reading.
The highlight and shadow boundaries can be adjusted in Settings. Colour targets and the skin-tone line are comparison guides, not a requirement that every subject must match them.
Select an area
Use an image region to measure one part of the picture. The rest of the image is left out of the scope readings.
- Open Settings → Region and measurement.
- Tap Capture source preview to capture the current image.
- Drag a rectangle over the part you want to measure. You can also enter the start and end coordinates and tap Apply ROI.
- Return to Scopes to see the measurements for your selection.
- Tap Reset region when you want to measure the whole frame again.
Isolate a colour
Limit the scope readings to a colour or a range of similar colours.
- Open Settings → Colour isolation.
- Under Analyse, choose Selected colour or Skin hue range.
- For a selected colour, tap Capture selection preview, then Pick colour from preview and tap the colour in the captured image.
- Open Refine selection to adjust hue tolerance, saturation and luma limits.
- Return to Scopes to measure the selected colours. Choose All colours to remove the filter.
The selection applies to all scopes, inside your chosen image region. Skin hue range selects colours, not faces; adjust it for your subject and lighting.
Compare or match a grade
Keep a scope trace as a reference while you adjust the grade. The reference appears over the live trace so you can compare them.
- With the image you want to remember on screen, tap Snap in that scope’s header.
- Adjust your grade in Resolve. The live trace updates while the saved reference stays in place.
- Tap A, B or C to show or hide each reference. They appear in red, green and blue.
- Open Controls → Overlay to adjust opacity. The starting value is 25%.
- Tap Clear in the scope header to remove its references. Use Clear all snapshots in Settings to remove every saved reference.
Each scope keeps three references. A fourth capture replaces the oldest. A reference with an incompatible range or colour space is hidden until the settings match.
References stay in that browser on that device and are separate from settings files. Clearing browser data can remove them.
Keep your preferred setup
The viewer remembers your settings in the current browser. Use Save settings to save a settings file, and Load settings to open one on another device. On phones and tablets, the browser may put saved files in Downloads; use the Files app or browser download menu to find them.
Reset to defaults restores the starting setup. Settings files do not include saved A/B/C scope references.
Quality changes the display resolution of the plots. Auto is a good starting point; lowering it can help a slower device. It does not change the chosen image region. Keep Debug off for normal use.
If something isn’t working
The page will not open
Check that the host is still running on the Mac and both devices are on the same local network. Use the current address in GTap’s panel. Allow incoming local connections if the Mac firewall asks. Guest Wi-Fi, a VPN or network isolation can prevent devices from reaching each other.
The page opens, but there is no trace
Tap Start listening. Check that GTap is enabled on a node in the current clip and the panel says the host is connected. Play, scrub or change a grade to send a frame. Check that the scope is not Off and that a colour selection or small region is not excluding the picture.
The levels or colours look wrong
Check GTap’s node position, declared input primaries and the viewer’s level range. A transform after GTap will not appear in the measurements. Reset the image region and colour selection to include the whole image.
The scopes update slowly
Try fewer scopes, a lower display Quality and a stronger local network connection. Source-coloured waveforms can be demanding. Update speed depends on the picture, Mac, browser and receiving device.
GTap does not appear in Resolve
Quit Resolve, rerun the installer and check its result. Reopen Resolve and check the Effects library. If macOS blocks the effect, review the message in Privacy & Security. The supplied effect is not notarized.
The screen dims or fullscreen closes
Browsers can limit keeping the display awake and fullscreen. Check the device’s auto-lock setting.
For a problem report, include your Mac and device models, OS and browser versions, Resolve version and what you were doing. Report an issue on GitHub.
Licence & credits
Ghetto Scopez and GTap are made by Vidar Andersen. Project website · Source code
The project’s original code, documentation and supplied header artwork are offered under Creative Commons Attribution–NonCommercial–ShareAlike 4.0 International (CC BY-NC-SA 4.0), to the extent the author holds the rights. Credit Vidar Andersen, link the licence and state any changes. Commercial use is not permitted by this licence. Share adaptations under the same licence. See the full licence for the terms.
Third-party components keep their own licences:
- OpenFX support library — The Open Effects Association, BSD 3-Clause.
- NoSleep.js 0.12.0 — Rich Tibbett, MIT.
- ws 8.22.0 — its authors and contributors, MIT.
- Three.js 0.186.1 — its authors and contributors, MIT; included host dependency.
- zlib — Jean-loup Gailly and Mark Adler, zlib licence; supplied by macOS.
Read the full third-party notices. Node.js is installed automatically when needed, under its own licence and notices. DaVinci Resolve, macOS and Apple frameworks are separately licensed products; they are not included in this download. This project is not affiliated with or endorsed by Blackmagic Design or Apple.
Additional acknowledgements
Header artwork supplied by the tears of real artist. Web versions resized and converted with Pillow (HPND licence) and libwebp (BSD 3-Clause). Coding assistance: OpenAI Codex, a proprietary service. Python (PSF licence), NumPy (BSD 3-Clause) and tifffile (BSD 3-Clause) were also used for validation. These tools are not included in the application download.