Remove matplotlib and generate color palette to mimic matplotlib's colors (#12327)

docker/main/requirements-wheels.txt

@@ -4,7 +4,6 @@ Flask_Limiter == 3.7.*
 imutils == 0.5.*
 joserfc == 0.11.*
 markupsafe == 2.1.*
-matplotlib == 3.8.*
 mypy == 1.6.1
 numpy == 1.26.*
 onvif_zeep == 0.2.12

frigate/config.py

@@ -7,7 +7,6 @@ from enum import Enum
 from pathlib import Path
 from typing import Any, Dict, List, Optional, Tuple, Union
 
-import matplotlib.pyplot as plt
 import numpy as np
 from pydantic import (
     BaseModel,
@@ -43,6 +42,7 @@ from frigate.plus import PlusApi
 from frigate.util.builtin import (
     deep_merge,
     escape_special_characters,
+    generate_color_palette,
     get_ffmpeg_arg_list,
     load_config_with_no_duplicates,
 )
@@ -1033,10 +1033,11 @@ class CameraConfig(FrigateBaseModel):
     def __init__(self, **config):
         # Set zone colors
         if "zones" in config:
-            colors = plt.cm.get_cmap("tab10", len(config["zones"]))
+            colors = generate_color_palette(len(config["zones"]))
+
             config["zones"] = {
-                name: {**z, "color": tuple(round(255 * c) for c in colors(idx)[:3])}
-                for idx, (name, z) in enumerate(config["zones"].items())
+                name: {**z, "color": color}
+                for (name, z), color in zip(config["zones"].items(), colors)
             }
 
         # add roles to the input if there is only one

frigate/detectors/detector_config.py

@@ -5,13 +5,12 @@ import os
 from enum import Enum
 from typing import Dict, Optional, Tuple
 
-import matplotlib.pyplot as plt
 import requests
 from pydantic import BaseModel, ConfigDict, Field
 from pydantic.fields import PrivateAttr
 
 from frigate.plus import PlusApi
-from frigate.util.builtin import load_labels
+from frigate.util.builtin import generate_color_palette, load_labels
 
 logger = logging.getLogger(__name__)
 
@@ -128,10 +127,9 @@ class ModelConfig(BaseModel):
 
     def create_colormap(self, enabled_labels: set[str]) -> None:
         """Get a list of colors for enabled labels."""
-        cmap = plt.cm.get_cmap("tab10", len(enabled_labels))
+        colors = generate_color_palette(len(enabled_labels))
 
-        for key, val in enumerate(enabled_labels):
-            self._colormap[val] = tuple(int(round(255 * c)) for c in cmap(key)[:3])
+        self._colormap = {label: color for label, color in zip(enabled_labels, colors)}
 
     model_config = ConfigDict(extra="forbid", protected_namespaces=())
 

frigate/util/builtin.py

@@ -349,3 +349,39 @@ def empty_and_close_queue(q: mp.Queue):
             q.close()
             q.join_thread()
             return
+
+
+def generate_color_palette(n):
+    # mimic matplotlib's color scheme
+    base_colors = [
+        (31, 119, 180),  # blue
+        (255, 127, 14),  # orange
+        (44, 160, 44),  # green
+        (214, 39, 40),  # red
+        (148, 103, 189),  # purple
+        (140, 86, 75),  # brown
+        (227, 119, 194),  # pink
+        (127, 127, 127),  # gray
+        (188, 189, 34),  # olive
+        (23, 190, 207),  # cyan
+    ]
+
+    def interpolate(color1, color2, factor):
+        return tuple(int(c1 + (c2 - c1) * factor) for c1, c2 in zip(color1, color2))
+
+    if n <= len(base_colors):
+        return base_colors[:n]
+
+    colors = base_colors.copy()
+    step = 1 / (n - len(base_colors) + 1)
+    extra_colors_needed = n - len(base_colors)
+
+    # interpolate between the base colors to generate more if needed
+    for i in range(extra_colors_needed):
+        index = i % (len(base_colors) - 1)
+        factor = (i + 1) * step
+        color1 = base_colors[index]
+        color2 = base_colors[index + 1]
+        colors.append(interpolate(color1, color2, factor))
+
+    return colors