Quick Start

This guide walks through previewing a colormap, checking it, saving it, and exporting it. The same steps work from Python.

Try without installing

You can run any command with uvx palettize instead of palettize to use the tool without installing it:

uvx palettize show viridis

Preview a Colormap

The show command renders a colormap preview directly in your terminal:

# Show a built-in preset
palettize show viridis

# Show a custom gradient
palettize show --colors "midnightblue,orange,gold"

# Or use uvx to run without installing
uvx palettize show viridis

You can adjust the preview, reverse it, or write an image:

palettize show viridis --width 80 --height 3
palettize show viridis --steps 7 --hex
palettize show viridis --reverse -o preview.png

Check a Colormap

analyze reports lightness, perceptual step size, and how the map looks under protanopia, deuteranopia, and tritanopia:

palettize analyze cividis
palettize analyze jet --strict   # non-zero exit when problems are found

Export a Colormap

The create command exports colormaps to various file formats:

# Export viridis to GDAL format with a data domain of 0-255
palettize create viridis --format gdal --output viridis.txt --domain 0,255

Custom Colors

Instead of using a preset, you can define your own colors:

palettize create --colors "blue,white,red" --format gdal --output bwr.txt --domain 0,100

Multiple Formats

Export to multiple formats at once using the {name}, {format}, and {ext} placeholders:

palettize create viridis --format gdal,qgis,mapgl \
  --output "output/{name}_{format}.{ext}" \
  --domain 0,255 \
  --steps 11

This creates:

• output/viridis_gdal.txt
• output/viridis_qgis.xml
• output/viridis_mapgl.json

Save and Reuse

--save writes a JSON file. Any command that takes a preset also accepts that file:

palettize create viridis --cut 0.2,0.8 --reverse --save my-map.json
palettize show my-map.json
palettize create my-map.json -f css -o theme.css

Find a Preset or a Format

palettize list presets --search blue --category sequential
palettize formats
palettize formats gdal

Using from Python

Palettize can also be used as a library:

from palettize import create_colormap, get_scaler_by_name

# Create a colormap from a preset
cmap = create_colormap(preset="viridis", name="Viridis")

# Get a color at a specific position (0-1)
hex_color = cmap.get_color(0.5)  # Returns "#21918d"
rgb = cmap.get_color(0.5, output_format="rgb_tuple")  # Returns (33, 145, 141)

# Create from custom colors
cmap2 = create_colormap(
    colors=["#0000ff", "white", "#ff0000"],
    name="BlueWhiteRed"
)

# Use a scaler to map data values to colors
scaler = get_scaler_by_name("linear", domain_min=0, domain_max=100)
color_at_50 = cmap2.apply_scaler(50, scaler)  # Color at the midpoint

Next Steps

• Learn about all CLI commands
• Explore the Python API
• See all Export Formats
• Understand Color Interpolation
• Transform and save colormaps