Gamut Viewer

Gamut Viewer

View Gamut opens a window that shows printable colour as a 3D shape. The shape is called a gamut.

Use it to answer questions such as:

• How much of sRGB can this paper hold?
• Does the new profile cover more reds than last year's profile on the same paper?
• Is this Lab value inside the paper or outside it?

It does not preview a photograph. It does not run ColorSync on an image. For that you still use your usual editor and the installed ICC.

Open the window

• Sidebar: View Gamut. Works even when you have no printer profile yet. You then see only the sRGB reference.
• Step 5: View Gamut. Loads the current profile's shape when a matching gamut file exists.

Close the window with the Close button (or the window close control) when you do not need it. On older Macs the 3D view uses a noticeable amount of graphics power.

What you are looking at

The view uses CIE Lab.

• Up and down is Lightness (L). White is toward the top, black toward the bottom.
• Left and right is a (green to red).
• Near and far is b (blue to yellow).

A closed surface is the outer limit of colours in that layer. A colour inside the surface can be represented by that space. A colour outside cannot.

Layers

Three checkboxes sit above the view.

• sRGB. A built-in reference for typical screen colour. It always loads. You can hide it. You cannot remove it.
• Profile. The current session's printer gamut, when ICCery has a .gam file next to the ICC.
• Compare. A second printer gamut you add. The checkbox stays off until a compare file is loaded.

Each visible layer is drawn as a translucent hull. sRGB is drawn more quietly so a printer layer can sit on top of it.

The checkboxes stay usable even when this Mac cannot start the 3D view. You can still load a compare file and inspect Lab values; you just will not see a mesh.

Add a second profile

Click Add compare and choose one of:

• Open .gam. An existing gamut file from a previous ICCery or Argyll session.
• Open profile. An .icc, .icm, or .mpp file. If there is no gamut file next to it, ICCery builds one and waits. A progress caption appears while that runs.

Only two printer layers are kept. Adding a third replaces the compare layer. Remove compare drops the extra layer and leaves sRGB and Profile as they were.

When the 3D view cannot start

On some Macs (no Metal, or a graphics session that failed to start) the 3D view is replaced by a short message that the viewer is unavailable. The rest of ICCery still works. You can still:

• See which layers are loaded
• Turn layers on and off
• Type a Lab value and inspect it
• Read the status line

You cannot orbit a mesh that was never drawn. This is a limit of the graphics session, not a missing profile.

Move the camera

• Drag in the view to orbit.
• Reset view, or press R when the view is focused, to return to the starting camera.

Reset does not reload files and does not change which layers are ticked.

Status line

Under the view you see how large each loaded mesh is (vertices and faces) and, when both volumes can be measured, how the printer volume compares with sRGB.

Inspected Lab values are not repeated here. They live in the inspect panel so the status line stays still.

Inspect a colour

The panel under the view is always the same height, whether or not you have picked a colour.

You can inspect in three ways:

1. Click the mesh. The nearest surface point becomes the sample.
2. Type L, a, and b, then click Inspect.
3. Sample TIFF. Choose an image, then click a pixel. The Lab value is an estimate from that pixel's colour, labelled Approximate. It is not a ColorSync conversion through your new profile.

For each loaded layer the panel says whether that Lab value is inside or outside the hull. You also see the Lab numbers and a swatch.

Paper white sits near L 95 to 100 with a and b close to 0. A deep red sits at a high positive a. If Inspect says a saturated screen red is outside the printer layer, that colour will clip on that paper.

Files behind the view

A .gam file next to an ICC is the mesh. Step 4 tries to write one when it builds a profile. If that step failed, Open profile from Add compare can build the mesh later. The ICC itself is enough to print. The extra file is only for this window.