Pillow grayscale

Skill cxcscmu/SkillLearnBench/skills/b1-one-shot-claude-sonnet-4-6/video-object-counting/pillow-grayscale

Convert images to grayscale in-place using Pillow (PIL), overwriting original RGB files.From its SKILL.md

Install

npx -y skills add cxcscmu/SkillLearnBench --skill pillow-grayscale

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SKILL.md

1.2 KB, 283 tokens by cl100k_base, as published. Nobody here has run it

Pillow Grayscale Conversion

Installation

pip install Pillow

Convert Single Image In-Place

from PIL import Image

def convert_to_grayscale_inplace(image_path):
    img = Image.open(image_path)
    gray = img.convert("L")      # "L" mode = 8-bit grayscale
    gray.save(image_path)        # overwrite the original file

Convert Multiple Images

from PIL import Image
import glob

def batch_convert_grayscale(pattern):
    for path in glob.glob(pattern):
        img = Image.open(path).convert("L")
        img.save(path)

Modes Reference

Mode	Description
`"L"`	8-bit grayscale (0-255)
`"RGB"`	24-bit color
`"RGBA"`	32-bit color with alpha
`"1"`	1-bit black & white

Notes

.convert("L") handles all source formats (RGB, RGBA, etc.)
Saving back to PNG preserves lossless quality
After conversion, the file on disk is grayscale but retains the .png extension
OpenCV's cv2.imread() will still read the file; use cv2.IMREAD_GRAYSCALE or the image will have 3 identical channels

What ships with it

Read from the repository

Just SKILL.md. No reference files, no scripts.