Images and graphics are the backbone of digital design, bringing life to websites and apps. They're not just pretty pictures—they're powerful tools that communicate ideas, evoke emotions, and guide users through digital experiences.

From vector logos to data-rich infographics, designers have a vast toolkit at their disposal. Understanding file formats, resolution, and optimization techniques is crucial for creating visually stunning and performant designs that work across all devices.

Image Types and Formats

Vector vs. Raster Graphics

• Vector graphics use mathematical equations to define shapes and lines
  • Remain crisp and clear at any size without losing quality
  • Ideal for logos, illustrations, and icons
  • Common file formats include SVG, AI, and EPS
• Raster images consist of a grid of individual pixels
  • Resolution-dependent, may lose quality when enlarged
  • Suitable for photographs and complex images with many colors
  • Popular formats include JPEG, PNG, and GIF

Image Resolution and Aspect Ratio

• Image resolution measures the number of pixels in an image
  • Expressed in pixels per inch (PPI) or dots per inch (DPI)
  • Higher resolution results in sharper, more detailed images
  • Web images typically use 72 PPI, while print requires 300 DPI or higher
• Aspect ratio defines the proportional relationship between width and height
  • Common ratios include 16:9 (widescreen), 4:3 (standard), and 1:1 (square)
  • Maintaining aspect ratio prevents image distortion when resizing
  • Cropping can adjust aspect ratio while preserving image quality

Image Compression and File Formats

• Image compression reduces file size to optimize storage and loading times
  • Lossless compression preserves all original data (PNG, GIF)
  • Lossy compression discards some data to achieve smaller file sizes (JPEG)
• JPEG (Joint Photographic Experts Group)
  • Ideal for photographs and complex images with many colors
  • Supports variable compression levels to balance quality and file size
• PNG (Portable Network Graphics)
  • Supports transparency and lossless compression
  • Best for images with text, logos, or sharp edges
• GIF (Graphics Interchange Format)
  • Limited to 256 colors, supports animation
  • Suitable for simple graphics and short animations

Sourcing and Using Images

Stock Photography and Licensing

• Stock photography provides pre-made images for commercial use
  • Royalty-free licenses allow unlimited use after a one-time payment
  • Rights-managed licenses restrict usage based on specific terms
• Popular stock photo websites include Shutterstock, Adobe Stock, and Unsplash
• Creative Commons licenses offer free-to-use images with varying restrictions
  • CC0 allows unrestricted use without attribution
  • CC BY requires attribution to the original creator
• Always verify licensing terms before using any image in your designs

Image Optimization and Performance

• Image optimization improves website loading times and user experience
  • Resize images to the exact dimensions needed for display
  • Use appropriate file formats based on image content (JPEG for photos, PNG for graphics)
  • Implement lazy loading to defer off-screen images until needed
• Content Delivery Networks (CDNs) distribute images across multiple servers
  • Reduces load times by serving images from geographically closer locations
  • Improves scalability and reliability of image delivery
• Responsive images adapt to different screen sizes and resolutions
  • Use HTML srcset attribute to provide multiple image versions
  • CSS media queries can adjust image display based on device characteristics

Accessibility and Alt Text

• Alt text provides textual descriptions of images for screen readers
  • Improves accessibility for visually impaired users
  • Helps search engines understand image content for better SEO
• Best practices for writing effective alt text
  • Be concise and descriptive, focusing on the image's purpose
  • Avoid redundant phrases like "image of" or "picture of"
  • Use empty alt attributes for decorative images (alt="")
• ARIA (Accessible Rich Internet Applications) roles can enhance image accessibility
  • Use role="img" for non-<img> elements that function as images
  • Combine with aria-label to provide descriptions for complex graphics

Visual Data Representation

Infographics and Information Design

• Infographics combine text, images, and data visualizations to convey complex information
  • Use visual hierarchy to guide viewers through the information
  • Employ consistent color schemes and typography for cohesive design
  • Balance text and visuals to maintain reader engagement
• Key elements of effective infographics
  • Clear and concise headlines that capture the main message
  • Icons and illustrations to represent concepts visually
  • Data visualizations (charts, graphs) to present numerical information
  • Source citations to establish credibility and transparency

Data Visualization Techniques

• Charts and graphs translate numerical data into visual representations
  • Bar charts compare values across categories
  • Line graphs show trends over time
  • Pie charts display proportions of a whole
  • Scatter plots reveal relationships between variables
• Interactive data visualizations engage users and provide deeper insights
  • Tooltips reveal additional information on hover or click
  • Filters allow users to explore specific data subsets
  • Animations highlight changes or transitions in data
• Choosing the right visualization type depends on the data and message
  • Consider the data structure (categorical, temporal, hierarchical)
  • Align the visualization with the story you want to tell
  • Test different options to find the most effective representation