Per-Class Specificity

Available

image_classification.per_class_specificity

Specificity computed separately for each class label, emitted as a per-class breakdown alongside the macro-average score.

Contract

Field	Value
version	1.0.0
metric_type	pointwise
scorer_contract	full_dataset
direction	higher_is_better
entrypoint	aip_scorers_image_classification.answered.per_class_specificity
target_kind	None

Required columns

• image_id
• label
• predictions

Accepted schemas

[
  {
    "name": "gdi_image_v1",
    "task_types": [
      "classification"
    ]
  }
]

Methodology

1. Deterministic - no LLM. Derived from the confusion matrix (numpy counts).
2. Compute per-class specificity = TN / (TN + FP) for every class, with undefined rates rendered as 0.0.
3. Emit the per-class specificities as an artifact keyed by class name.
4. Report the macro-average specificity as the scalar score.

Score semantics

The scalar score is the macro-average specificity (0-1); the artifact reports each class's specificity by name. A high score means the model rarely over-assigns each class. Higher is better.

Worked example

Confusion matrix [[1, 1], [0, 2]] emits {cat: 1.0, dog: 0.5} and a scalar macro-average of 0.75.

Configuration schema

{
  "description": "Shared image-classification metric configuration.",
  "properties": {
    "inverted": {
      "default": false,
      "title": "Inverted",
      "type": "boolean",
      "x-aip-param-role": "scoring_metadata"
    },
    "max": {
      "default": 1.0,
      "title": "Max",
      "type": "number",
      "x-aip-param-role": "scoring_metadata"
    },
    "metric_name": {
      "default": "image_classification_metric",
      "title": "Metric Name",
      "type": "string",
      "x-aip-param-role": "scoring_metadata"
    },
    "min": {
      "default": 0.0,
      "title": "Min",
      "type": "number",
      "x-aip-param-role": "scoring_metadata"
    },
    "weight": {
      "default": 1.0,
      "title": "Weight",
      "type": "number",
      "x-aip-param-role": "scoring_metadata"
    }
  },
  "title": "InitializationConfig",
  "type": "object"
}

Execution

{
  "emits_metric_family": false,
  "function_name": null,
  "max_concurrency": null,
  "processing_kind": "cpu",
  "stream_batch_size": null,
  "timeout_seconds": 600
}

Complete manifest

accepts:
- name: gdi_image_v1
  task_types:
  - classification
config_schema:
  description: Shared image-classification metric configuration.
  properties:
    inverted:
      default: false
      title: Inverted
      type: boolean
      x-aip-param-role: scoring_metadata
    max:
      default: 1.0
      title: Max
      type: number
      x-aip-param-role: scoring_metadata
    metric_name:
      default: image_classification_metric
      title: Metric Name
      type: string
      x-aip-param-role: scoring_metadata
    min:
      default: 0.0
      title: Min
      type: number
      x-aip-param-role: scoring_metadata
    weight:
      default: 1.0
      title: Weight
      type: number
      x-aip-param-role: scoring_metadata
  title: InitializationConfig
  type: object
dependencies: []
description: Specificity for each class label, emitted as a per-class score artifact.
direction: higher_is_better
display_name: Per-Class Specificity
entrypoint: aip_scorers_image_classification.answered.per_class_specificity
execution:
  emits_metric_family: false
  function_name: null
  max_concurrency: null
  processing_kind: cpu
  stream_batch_size: null
  timeout_seconds: 600
kind: metric
manifest_version: '1'
max_prompt_slots: 0
metric_metadata:
  methodology:
  - Deterministic - no LLM. Derived from the confusion matrix (numpy counts).
  - Compute per-class specificity = TN / (TN + FP) for every class, with undefined
    rates rendered as 0.0.
  - Emit the per-class specificities as an artifact keyed by class name.
  - Report the macro-average specificity as the scalar score.
  score_semantics: The scalar score is the macro-average specificity (0-1); the artifact
    reports each class's specificity by name. A high score means the model rarely
    over-assigns each class. Higher is better.
  summary: Specificity computed separately for each class label, emitted as a per-class
    breakdown alongside the macro-average score.
  worked_example: 'Confusion matrix [[1, 1], [0, 2]] emits {cat: 1.0, dog: 0.5} and
    a scalar macro-average of 0.75.'
metric_type: pointwise
name: image_classification.per_class_specificity
partition_types: []
required_columns:
- image_id
- label
- predictions
required_kinds: []
scorer_contract: full_dataset
target_kind: null
unsupported_trace_shapes: []
version: 1.0.0