Resolution and Aspect Ratio

• Resolution
  Dots per unit length.
• Image size
  Number of dots, or pixels, in the image.
• Aspect ratio
  Ratio of rows to columns in the pixel grid.
• Pixel aspect ratio
  Exact shape ($\Delta x : \Delta y$) of a single pixel.

Physical dimensions of the image follow from these, with $R$ defined along the vertical axis so the vertical dot pitch is $1/R$ and the horizontal dot pitch is $\frac{\Delta x}{\Delta y} \cdot \frac{1}{R}$.

Here:

• $R$: resolution in dots per unit length
• $N_c$: number of columns
• $N_r$: number of rows
• $\Delta x : \Delta y$: pixel aspect ratio

For square pixels $\Delta x = \Delta y$, so $\text{width} = N_c / R$.

Changing Geometry

• Changing resolution affects image granularity, potentially causing a checkerboard effect when upscaling
• Changing pixel count affects file size
• Changing physical pixel size or aspect ratio affects object geometry, potentially causing distortion