Image Gen

Image Generation & Processing

Quick Reference

Pillow — Image Processing

Resize and crop

from PIL import Image

img = Image.open("input.jpg")

# Resize maintaining aspect ratio
img.thumbnail((800, 600))
img.save("resized.jpg")

# Exact resize (may distort)
img_resized = img.resize((800, 600))

# Crop (left, upper, right, lower)
cropped = img.crop((100, 50, 500, 400))
cropped.save("cropped.jpg")

# Center crop to square
w, h = img.size
size = min(w, h)
left = (w - size) // 2
top = (h - size) // 2
square = img.crop((left, top, left + size, top + size))

Filters and adjustments

from PIL import ImageFilter, ImageEnhance

# Blur / sharpen
blurred = img.filter(ImageFilter.GaussianBlur(radius=3))
sharpened = img.filter(ImageFilter.SHARPEN)

# Brightness, contrast, saturation
enhancer = ImageEnhance.Brightness(img)
bright = enhancer.enhance(1.3)  # 1.0 = original

enhancer = ImageEnhance.Contrast(img)
contrast = enhancer.enhance(1.5)

# Convert to grayscale
gray = img.convert("L")

Compositing and watermarks

from PIL import Image, ImageDraw, ImageFont

img = Image.open("photo.jpg")
draw = ImageDraw.Draw(img)

# Text watermark
font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf", 36)
draw.text((20, img.height - 50), "© 2025", fill=(255, 255, 255, 128), font=font)

# Overlay image (logo in corner)
logo = Image.open("logo.png").resize((100, 100))
img.paste(logo, (img.width - 110, 10), logo)  # third arg = mask for transparency

img.save("watermarked.jpg")

Pillow — Creating Graphics from Scratch

Banner / social media graphic

from PIL import Image, ImageDraw, ImageFont

W, H = 1200, 630  # Open Graph size
img = Image.new("RGB", (W, H), "#1E2761")
draw = ImageDraw.Draw(img)

# Background accent shape
draw.rectangle([(0, H - 80), (W, H)], fill="#F96167")

# Title text
font_title = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf", 64)
font_sub = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf", 28)
# Install fonts if missing: apt install fonts-dejavu-core

# Center title
bbox = draw.textbbox((0, 0), "Project Launch", font=font_title)
tw = bbox[2] - bbox[0]
draw.text(((W - tw) // 2, 200), "Project Launch", fill="white", font=font_title)

# Subtitle
bbox = draw.textbbox((0, 0), "Coming Q2 2025", font=font_sub)
tw = bbox[2] - bbox[0]
draw.text(((W - tw) // 2, 300), "Coming Q2 2025", fill="#CADCFC", font=font_sub)

img.save("banner.png")

Grid / contact sheet

from PIL import Image
import glob

images = [Image.open(f) for f in sorted(glob.glob("photos/*.jpg"))[:9]]
thumb_size = (300, 300)
cols, rows = 3, 3
padding = 10
bg_color = "#0A0A0A"

canvas_w = cols * thumb_size[0] + (cols + 1) * padding
canvas_h = rows * thumb_size[1] + (rows + 1) * padding
canvas = Image.new("RGB", (canvas_w, canvas_h), bg_color)

for i, img in enumerate(images):
    img.thumbnail(thumb_size)
    r, c = divmod(i, cols)
    x = padding + c * (thumb_size[0] + padding)
    y = padding + r * (thumb_size[1] + padding)
    canvas.paste(img, (x, y))

canvas.save("grid.png")

Diagrams with matplotlib

Flowchart

import matplotlib.pyplot as plt
import matplotlib.patches as mpatches

fig, ax = plt.subplots(figsize=(10, 8))
ax.set_xlim(0, 10)
ax.set_ylim(0, 10)
ax.axis('off')

def add_box(ax, x, y, text, color='#1E2761', w=2.5, h=0.8):
    rect = mpatches.FancyBboxPatch((x - w/2, y - h/2), w, h,
        boxstyle="round,pad=0.1", facecolor=color, edgecolor='white', linewidth=1.5)
    ax.add_patch(rect)
    ax.text(x, y, text, ha='center', va='center', fontsize=11,
            color='white', fontweight='bold')

def add_arrow(ax, x1, y1, x2, y2):
    ax.annotate('', xy=(x2, y2), xytext=(x1, y1),
        arrowprops=dict(arrowstyle='->', color='#888888', lw=1.5))

add_box(ax, 5, 9, "Start")
add_arrow(ax, 5, 8.6, 5, 7.8)
add_box(ax, 5, 7.4, "Process Data")
add_arrow(ax, 5, 7.0, 5, 6.2)
add_box(ax, 5, 5.8, "Analyze Results")
add_arrow(ax, 5, 5.4, 5, 4.6)
add_box(ax, 5, 4.2, "Generate Report", color='#2C5F2D')

plt.tight_layout()
plt.savefig('flowchart.png', dpi=150, bbox_inches='tight', facecolor='#0A0A0A')

SVG — Simple Vector Graphics

svg = '''<svg xmlns="http://www.w3.org/2000/svg" width="400" height="300" viewBox="0 0 400 300">
  <rect width="400" height="300" fill="#0A0A0A"/>
  <circle cx="200" cy="150" r="80" fill="none" stroke="#C0C0C0" stroke-width="2"/>
  <text x="200" y="155" text-anchor="middle" fill="#E8E8E8"
        font-family="system-ui" font-size="18" font-weight="bold">
    Logo Text
  </text>
</svg>'''

with open("icon.svg", "w") as f:
    f.write(svg)

Animated GIF

from PIL import Image, ImageDraw

frames = []
W, H = 400, 400

for i in range(30):
    img = Image.new("RGB", (W, H), "#0A0A0A")
    draw = ImageDraw.Draw(img)
    x = int(i / 29 * (W - 60))
    draw.ellipse([x, 170, x + 60, 230], fill="#F96167")
    frames.append(img)

frames[0].save("animation.gif", save_all=True, append_images=frames[1:],
               duration=50, loop=0, optimize=True)

Common Image Sizes

Quality Rules

• Always set DPI: plt.savefig(..., dpi=150) minimum
• Use tight layout: bbox_inches='tight' to avoid clipping
• Label everything: axes, legends, titles on charts
• Consistent palette: pick 3–5 colors and reuse them
• Check contrast: text must be readable against background
• Save PNG for graphics (lossless), JPEG for photos (smaller)