Metadata Configuration File

In certain situations, information to run a test is not available in the file metadata. Some examples include:

• No aperture information for manual aperture lenses
• No aperture/focal length information for adapted lenses
• Missing focus adjustment (AF Microadjustment, AF Fine Tune etc) information for cameras that do not supply this information in the file

FoCal offers a way for you to supply this information through the use of a configuration file.

The meta.json file

In order to supply missing metadata about files, you need to create a text file called meta.json and place it in the same directory as the files you will be analysing.

An example meta.config file is shown below:

[
  {
    "filenames": ["30", "31", "32"],
    "afType": "live",
    "afmaActive": true,
    "shotAFMA": -20
  },
  {
    "filenames": ["33", "34", "35"],
    "afType": "live",
    "afmaActive": true,
    "shotAFMA": -10
  },
  {
    "filenames": ["36", "37", "38"],
    "afType": "live",
    "afmaActive": true,
    "shotAFMA": 0
  },
  {
    "filenames": ["39", "40", "41"],
    "afType": "live",
    "afmaActive": true,
    "shotAFMA": 10
  },
  {
    "filenames": ["42", "43", "44"],
    "afType": "live",
    "afmaActive": true,
    "shotAFMA": 20
  }
  
]

Metadata config file options

Overview

The metadata config file is a json file (JavaScript Object Notation) – this is a flexible and well documented standard for defining information.

Key points:

• The file must be enclosed in square brackets as shown above (this is the json notation for an array)
• Each set of metadata that you want to apply to one or more files must be enclosed in curly braces (this is the json notation for an object)
• Each object must contain a selector – either filename or filenames – and then one or more metadata specifiers.
• Keys and values are separated with a colon.
• The name for each key (e.g. filename or afType) must be within quotes.
• Numbers and Boolean (true/false) values are NOT enclosed in quotes, but all other values should be.

Selecting Files

Each metadata set contains a selector which is either filename or filenames:

filename

Specify part or all of a single filename. For example, you could use set img123.jpg to match a single file, or 123 to match any file with the number 123 in the filename.

Example:

“filename”: “123”

filenames

The same logic as filename is used, but you can supply an array of filename within square brackets to match a number of files. This is used in the example above.

Example:

“filename”: [“30”, “31”, “32”]

This will apply the defined metadata to all files that contain the values, e.g. IMG1230.jpg, IMG1231.arw, IMG1232.nef, photo_321.jpg (the bold part shows the match).

Metadata Values

The following options are available to specify to FoCal the metadata that should be applied to a file. Any user specified metadata will take precedence over the metadata contained within the file if present.

aperture

Numeric value to specify the aperture.

Example:

“aperture”: 5.6

shutterSpeed

Numeric value to specify the shutter speed.

Example:

“shutterSpeed”: 0.1

iso

Numeric value to specify the ISO.

Example:

“iso”: 200

focalLength

Numeric value to specify the focal length (in mm) used for the shot.

Example:

“focalLength”: 50

minFocalLength

Numeric value to specify the minimum focal length (in mm) of the lens.

Example:

“minFocalLength”: 24

maxFocalLength

Numeric value to specify the maximum focal length (in mm) of the lens.

Example:

“maxFocalLength”: 70

lensSerialNumber

Text value to specify the lens serial number.

The value must be enclosed in quotes.

Example:

“lensSerialNumber”: “12341234”

focusDistance

Numeric value to specify the focus distance (in metres) for the shot.

Example:

“focusDistance”: 2.4

imageStabilisation

Boolean value (true/false) to specify if Image Stabilisation is active.

Example:

“imageStabilisation”: true

afmaActive

Boolean value (true/false) to specify if the Focus Adjustment is active. Note that this must be set to true in order for the shotAFMA value to be applied.

Example:

“afmaActive”: true

shotAFMA

Numeric value to specify the Focus Adjustment value applied for this shot.

Example:

“shotAFMA”: -7

defocusDir

Enumeration for the Defocus Direction. Options are:

• None
• Near
• Far

The value must be enclosed in quotes.

Example:

“defocusDir”: “None”

defocusAmount

Enumeration for the Defocus Amount. Options are:

• None
• Small
• Large

The value must be enclosed in quotes.

Example:

“defocusAmount”: “Small”

afType

Enumeration for the Autofocus Type. Options are:

• None
• PDAF
• Live

The value must be enclosed in quotes.

Example:

“afType”: “PDAF”