Projection Pixel Density

Calculate linear and angular pixel density for a projected image.

Description

Projected pixel density depends on both physical image width and viewing distance.

Projected pixel density depends on both physical image width and viewing distance. Linear density and pixels per visual degree answer different questions about apparent detail.^[1]

Calculate linear and angular pixel density for a projected image.

When to use Projection Pixel Density

Use this tool to calculate linear and angular pixel density for a projected image.

Prepare production measurements or checklist records for one planning period. Confirm units, staffing assumptions and caller-selected criteria before running the calculation.

How to use Projection Pixel Density and understand its results

Prepare production measurements or checklist records for one planning period. Confirm units, staffing assumptions and caller-selected criteria before running the calculation.
Enter horizontalPixels, imageWidthMeters, viewerDistanceMeters using the field table and calculation rules, then run the tool.
Read pixelsPerMeter, pixelPitchMillimeters, pixelsPerDegree. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
horizontalPixels	Horizontal resolution (px)	integer; minimum: 1	Required
imageWidthMeters	Projected image width (m)	number; minimum: 0	Required
viewerDistanceMeters	Viewer distance (m)	number; minimum: 0	Required

Enter positive integer horizontal pixels and strictly positive image width/viewing distance in meters. Compute linear density, pixel pitch and angular image width for pixels per degree.

pixelsPerMeter=pixels/width; pitchMm=1000/density; pixelsPerDegree=pixels/[2 atan(width/(2 distance)) in degrees]

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
pixelsPerMeter	Pixel density (px/m)	number; minimum: 0
pixelPitchMillimeters	Projected pixel pitch (mm)	number; minimum: 0
pixelsPerDegree	Angular pixel density (px/°)	number; minimum: 0

json

{
  "input": {
    "horizontalPixels": 3840,
    "imageWidthMeters": 8,
    "viewerDistanceMeters": 12
  },
  "output": {
    "pixelsPerMeter": 480,
    "pixelPitchMillimeters": 2.0833333333333335,
    "pixelsPerDegree": 104.15000434461052
  }
}

Limitations and assumptions

Image geometry is centered and flat. Optics, keystone, viewing angle, acuity and a recommended visibility threshold are not modeled.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Edge-Blend Overlap: Calculate overlap pixels and total blended width for a horizontal projector row. For a complementary task, use Pixel-Map Capacity: Calculate pixel-map canvas size and control-universe capacity.

References

Projection Pixel Density — tool.io

Similar or alternative tools

Edge-Blend Overlap
Calculate overlap pixels and total blended width for a horizontal projector row.
Pixel-Map Capacity
Calculate pixel-map canvas size and control-universe capacity.