QGIS Export Format

The QGIS exporter creates XML color ramp files that can be imported into QGIS for styling raster and vector layers.

Format Details

Property	Value
Identifier	qgis
Extension	.xml
Use case	QGIS desktop GIS styling

Output Format

<?xml version='1.0' encoding='utf-8'?>
<colorramps>
  <colorramp name="viridis" type="gradient">
    <item alpha="255" color="#440154" position="0.0000"/>
    <item alpha="255" color="#482878" position="0.1111"/>
    ...
    <item alpha="255" color="#fde725" position="1.0000"/>
  </colorramp>
</colorramps>

CLI Usage

# Basic export
palettize create viridis --format qgis --output viridis.xml --domain 0,255

# Gradient ramp with custom steps
palettize create viridis -f qgis -o viridis.xml --steps 11

# Exact (discrete) ramp
palettize create viridis -f qgis -o viridis.xml -O ramp_type=exact

# With tags
palettize create viridis -f qgis -o viridis.xml -O "tags=scientific;perceptual"

Python Usage

from palettize import create_colormap, get_scaler_by_name, get_exporter

cmap = create_colormap(preset="viridis")
scaler = get_scaler_by_name("linear", domain_min=0, domain_max=255)
exporter = get_exporter("qgis")

output = exporter.export(
    colormap=cmap,
    scaler=scaler,
    domain_min=0,
    domain_max=255,
    options={
        "num_colors": 11,
        "ramp_type": "gradient",
        "name": "Viridis",
        "tags": ["scientific", "perceptual"]
    }
)

Options

Option	Type	Default	Description
num_colors	int	256	Number of color steps for gradient ramps
ramp_type	str	"gradient"	Ramp type: "gradient", "exact", "approximate"
name	str		Name for the color ramp
tags	list[str]		Tags for organizing ramps
discrete	bool	False	Whether stops are discrete (for exact/approximate)
color_space	str		QGIS color space hint
opacity	float	1.0	Overall opacity (0.0-1.0)

Ramp Types

Gradient (Default)

Continuous interpolation between colors. Best for continuous data.

palettize create viridis -f qgis -o viridis.xml -O ramp_type=gradient

Exact

Uses original colormap stops. Best for categorical or classified data.

palettize create viridis -f qgis -o viridis.xml -O ramp_type=exact

Approximate

Similar to exact but allows interpolation hints.

palettize create viridis -f qgis -o viridis.xml -O ramp_type=approximate

Importing into QGIS

1. In QGIS, go to Settings > Style Manager
2. Click Import/Export > Import Item(s)
3. Select your exported .xml file
4. The color ramp will appear in your style library

Alternatively, copy the XML content directly into a .qml style file or use it in symbology settings.

Applying to Raster Layers

1. Right-click your raster layer > Properties
2. Go to Symbology tab
3. Select Singleband pseudocolor
4. Choose your imported color ramp from the dropdown
5. Set min/max values to match your data domain