Development

Development corresponds to the second main step in Exposure Map post-processing.

The "Development" term is an echo to analog/film photography. Regarding digital photography, it is a software process coded into the camera that converts raw image (most of the time not given to user) and final/output image.

Two development types are available:

Generic basic development directly implemented in the Speos Sensor System Exporter as described in the Generic Development section.
Customizable development done from an external python script, as described in the External Development section.

Generic Development

Parameters used in the development calculations are defined into the main Development key divided into 5 sub-keys:

Demosaizing Method
Linearization
Orientation
Color Saturation Correction
Colorimetry

Demosaizing Method

If the Bayer Matrix Type sub-key of the EMVA data key is set to a value different from None, a Demosaizing step is performed to get raw R, G and B channels.

4 methods are available:

bilinear
Malvar2004
Menon2007
DDFAPD

For more information on the methods, refer to the Bayer CFA Demosaicing and Mosaicing API Reference.

The Demosaizing Method key must specify one of those methods.

   Demosaizing Method: bilinear

Linearization

The Linearization key allows you to correct sensor non-linearity. If sensor is assumed to be linear, the Type sub-key must be set to None.

   Linearization:
      Type: None

If you want to correct the non-linearity, you have two possibilities:

1D lookup table (0 to max DN value)
polynomial correction (DN_out = sum(Pi*(DN_in)**i))

Orientation

The Orientation key allows you to change the image orientation and/or apply a symmetry:

1 = The 0^th row represents the visual top of the image, and the 0^th column represents the visual left-hand side.
2 = The 0^th row represents the visual top of the image, and the 0^th column represents the visual right-hand side.
3 = The 0^th row represents the visual bottom of the image, and the 0^th column represents the visual right-hand side.
4 = The 0^th row represents the visual bottom of the image, and the 0^th column represents the visual left-hand side.
5 = The 0^th row represents the visual left-hand side of the image, and the 0^th column represents the visual top.
6 = The 0^th row represents the visual right-hand side of the image, and the 0^th column represents the visual top.
7 = The 0^th row represents the visual right-hand side of the image, and the 0^th column represents the visual bottom.
8 = The 0^th row represents the visual left-hand side of the image, and the 0^th column represents the visual bottom.

Note: 1 and 3 values are mainly used:

1 keeps the original image.
3 balances an optical 180° rotation.

   Orientation: 3

Color Saturation Correction

The Color Saturation Correction sub-key can be set to True or False:

If True: an additional process corrects the color shifting due to pixel saturation.
If False: Color Saturation Correction is not applied.

   Color Saturation Correction: True

Colorimetry

The final image colorimetry depends on 3 inputs to be set into sub-keys:

Shoot Illuminant
Target Color Space
Adaptation method

From these inputs, 2 intermediate data are automatically calculated and added into the sensor file:

Camera Neutral vector
Color Calibration Matrix

Note: For more information on matrix, you can refer to the following websites Strollwithmydog and Brucelindbloom.

Therefore, the Colorimetry key is divided into 4 sub-keys:

Shoot Illuminant
Color Space
Adaptation Method
Configuration x

If colorimetric data have been previously calculated, an additional Configuration i (do not confuse it with Configuration x) is added to each combination of [Shoot Illuminant, Color Space, Adaptation method].

Shoot Illuminant

The Shoot Illuminant key gives the main illuminant used for the scene calculation with Speos.

The Type sub-key defines if the illuminant is predefined or comes from a Speos *.spectrum file.
The Data sub-key sets the predefined illuminants (A, B, C D50, D55, D65, or D75) or the *.spectrum file to use.

Example: Predefined Illuminant

   Shoot Illuminant:
      Type: Predefined
      Data: D50
      Unit: NA

In case of a Predefined illuminant, Unit sub-key is always set to NA.

Example: From File

   Shoot Illuminant:
      Type: File
      Data: c:/shoot.spectrum
      Unit: Percentage  #Percentage or '0 to 1'

Color Space

The Color Space key gives the color space in which the image will be targeted.

The available Color Space values are: sRGB, Adobe RGB (1998), Apple RGB, Best RGB, Beta RGB, Bruce RGB, CIE RGB, ColorMatch RGB, Don RGB 4, ECI RGB v2, Ekta Space PS5, NTSC RGB, PAL/SECAM RGB, ProPhoto RGB, SMPTE-C RGB, Wide Gamut RGB.

   Color Space: Best RGB

Adaptation Method

The Adaptation Method key defines the adaptation method used to switch from one to another color space.

Available methods are:

XYZ Scaling
Bradford
Von Kries

   Adaptation Method: Bradford

Configuration i

The Configuration i key contains data calculated during a previous post-process. As this calculation takes time, results are added to the file to allow you to reuse them.

Configuration x

The Configuration x key line should be present at the last line of the sensor file and kept as it is.

   Configuration x:    # please leave this line as it is.

External Development

How to call an external development

Instead of predefined development model, you can plug specific development algorithms called via a Python script.

To do that, the two following keys must be set in Development section:

Development:
   Type: External Script  #'Internal Generic' or 'External Script'
   External Script: Development.py

Script requirements

Script must be written in Python version superior to 3.10.12.

Script must contain a function named Development with:

two arguments:
- Rawimages: the set of raw images generated by the Speos Sensor System Exporter
- Sensors: the set of sensor data
one output: image data coded as a 3D numpy array (color channel, i, j)