Photoshop

Performing a measurement (Photoshop Extended)

You can measure using the Photoshop selection tools, Ruler tool, or Count tool. Choose a measurement tool that matches the kind of data you want to record in the Measurement Log.

  • Create a selection area to measure values such as height, width, perimeter, area, and pixel gray values. You can measure one selection or several selections at once.

  • Draw a line with the Ruler tool to measure linear distance and angle.

  • Use the Count tool to count items on the image, then record the number of items (see About counting (Photoshop Extended)).

    Each measurement measures one or more data points. The data points you select determine the information recorded in the Measurement log. Data points correspond to the type of tool you’re measuring with. Area, perimeter, height, and width are available data points for measuring selections. Length and angle are available data points for Ruler tool measurements. You can create and save sets of data points for particular types of measurements to speed your workflow.

  1. Open an existing document.
  2. Choose Analysis > Set Measurement Scale and choose a measurement scale preset for the document (see Set the measurement scale (Photoshop Extended)), or choose Custom and set a custom measurement scale.

    Measurements are computed and recorded in the Measurement Log using the scale units in effect when a measurement is recorded. If no measurement scale exists, the default scale is 1 pixel = 1 pixel.

  3. (Optional) Choose Analysis > Select Data Points and do one of the following:

    • Choose Custom to select data points to measure.

    • Select an existing data point preset from the submenu.

      For a video on understanding and using the measurement features, see www.adobe.com/go/vid0029.

    In the Select Data Points dialog box, data points are grouped according to the measurement tool that can measure them. The Common data points are available for all tools. They add useful information to the Measurement Log such as the name of the file being measured, the measurement scale, and the date/time of the measurement.

    By default all data points are selected. You can select a subset of data points for a particular kind of measurement and save the combination to make it available as a data point preset.

    Note: When you measure with a particular tool, only the data points associated that tool will be displayed in the log, even if other data points are selected. For example, if you make a measurement with the Ruler tool, only the Ruler tool data points will appear in the Measurement Log, along with any Common data points that are selected.
  4. Choose an image feature and measurement tool to match the selected data points. Do one of the following:

    • Create one or more selections on the image.

    • Choose Analysis > Ruler Tool, or click the Ruler tool in the toolbox, then use the tool to measure the length of an image area.

    • Choose Analysis > Count Tool, or click the Count tool in the toolbox, then count items in the image.

  5. Choose Window > Measurement Log to open the Measurement Log palette.
  6. Choose Analysis > Record Measurements, or click Record Measurements in the Measurement Log palette.
    Note: If your currently selected data points do not correspond to the your current measurement tool, you are asked to select data points for that tool.

    The Measurement log has columns for each data point you selected in the Measurement Data Points dialog box. Each measurement you make enters a new row of data in the Measurement Log.

    If you measure multiple selected areas on the image, one row of data is created in the log containing summary or cumulative data for all selected areas, followed by a row of data for each selection area. Each selection area is listed as a separate Feature in the Label column of the log and assigned a unique number.

    You can repeat steps 2 through 6 for a variety of different selections in the same or multiple documents. The Document column in the Measurement Log reflects the source of the measurement data.

Measurement Data Points

Angle
Angle of orientation (±0‑180) of the Ruler tool.

Area
Area of selection in square pixels, or in calibrated units according to the current measurement scale (such as square millimeters).

Circularity
4pi(area/perimeter2). A value of 1.0 indicates a perfect circle. As the value approaches 0.0, it indicates an increasingly elongated polygon. Values may not be valid for very small selections.

Count
Varies according to the measuring tool used. Selection tool: the number of discontiguous selection areas on the image. Count tool: the number of counted items on the image. Ruler tool: the number of Ruler lines visible (1 or 2).

Date and Time
Applies a date/time stamp of when the measurement occurred.

Document
Identifies the document (file) measured.

Gray Value
This is a measurement of brightness, either from 0 to 255 (for 8‑bit images), 0 to 32,768 (for 16‑bit images), or 0.0 to 10 (for 32‑bit images). For all gray value related measurements, the image is internally converted to grayscale (equivalent to choosing Image > Mode > Grayscale) using the default grayscale profile. Then the requested calculations (mean, median, minimum, maximum) are calculated for each feature and for the summary.

Height
Height of the selection (max y - min y), in units according to the current measurement scale.

Histogram
Generates histogram data for each channel in the image (three for RGB images, four for CMYK, and so on), recording the number of pixels at each value from 0 to 255 (16‑bit or 32‑bit values are converted to 8‑bit). When you export data from the Measurement Log, the numeric histogram data is exported to a CSV (comma separated value) file. The file is placed in its own folder at the same location where the measurement log tab-delimited text file is exported. Histogram files are assigned a unique number, starting at 0 and progressing by 1. For multiple selections measured at once, one histogram file is generated for the total selected area, plus additional histogram files for each selection.

Integrated Density
The sum of the values of the pixels in the selection. This is equivalent to the product of Area (in pixels) and Mean Gray Value.

Label
Identifies and automatically numbers each measurement as Measurement 1, Measurement 2, and so on. For multiple selections measured simultaneously, each selection is assigned an additional Feature label and number.

Length
Linear distance defined by the Ruler tool on the image, in units according to the current measurement scale.

Perimeter
The perimeter of the selection. For multiple selections measured at once, one measurement is generated for the total perimeter of all selections, plus additional measurements for each selection.

Scale
The measurement scale of the source document (for example, 100 px = 3 miles).

Scale Units
Logical units of the measurement scale.

Scale Factor
The number of pixels assigned to the scale unit.

Source
Source of the measurement: Ruler tool, Count Tool, or Selection.

Width
Width of the selection (max x - min x), in units according to the current measurement scale.

Create a data point preset

  1. Choose Analysis > Select Data Points > Custom.
  2. Select data points to include in the preset.
  3. Click Save Preset and name the preset.
  4. Click OK. The preset is saved and is now available from the Analysis > Select Data Points submenu.

Edit a data point preset

  1. Choose Analysis > Select Data Points > Custom.
  2. Choose the preset you want to edit from the Preset menu.
  3. Select or deselect data points. The Preset name changes to Custom.
  4. Click Save Preset. Enter the original preset name to replace the existing preset, or a new name to create a new preset.

Delete a data point preset

  1. Choose Analysis > Select Data Points > Custom.
  2. Choose the preset you want to delete from the Preset menu.
  3. Click Delete Preset, then Yes to confirm the deletion.
  4. Click OK.