Source: https://guthlabs.ai/docs/instruments/exposure-bracketing-hdr-stops-planner/implementation/

instrument implementation / implementation-contract

# Exposure Bracketing / HDR Stops Planner implementation

A source-bound implementation contract for Exposure Bracketing / HDR Stops Planner; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-252

**Effect**: Computation or source lookup only

## Input and validation requirements

The extreme valid-number input produces a non-finite Infinity output, and the specification does not define validation or rejection behavior. The unspecified frame-index and shutter-direction conventions can also produce reversed or differently centered bracket lists.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "base_seconds": 0.008,
    "number_of_frames": 3,
    "stop_step": 1,
    "n_indices": [
      -1,
      0,
      1
    ]
  },
  "expected_outputs": {
    "shutter_seconds": [
      0.004,
      0.008,
      0.016
    ]
  },
  "working": "For n=-1: 0.008*2^(-1*1)=0.008*(1/2)=0.004 s. For n=0: 0.008*2^(0*1)=0.008*1=0.008 s. For n=1: 0.008*2^(1*1)=0.008*2=0.016 s."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/exposure-bracketing-hdr-stops-planner/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/exposure-bracketing-hdr-stops-planner/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/exposure-bracketing-hdr-stops-planner/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`