WritersLogic Verifiable AI Agent Hub Exposure Calc API
The Exposure Calc API from WritersLogic Verifiable AI Agent Hub — 1 operation(s) for exposure calc.
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curl "https://apis.io/api/v1/apis/writerslogic-com:writerslogic-com-exposure-calc-api"
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OpenAPI Specification
openapi: 3.2.0
info:
title: WritersLogic Verifiable AI Agent Hub Exposure Calc API
version: 2.0.0
description: Pay-per-call agents settled in USDC on Base via x402. Every response carries a signed provenance envelope.
contact:
name: WritersLogic
url: https://writerslogic.com/agents
email: agents@writerslogic.com
servers:
- url: https://agents.writerslogic.com
tags:
- name: Exposure Calc
paths:
/api/v1/exposure-calc:
post:
operationId: exposure_calc
summary: 'Photographic exposure value: solve aperture, shutter, ISO or EV, with…'
description: 'Given any three of aperture (f-number), shutter time in seconds, ISO and scene EV at ISO 100, solves the fourth from EV = log2(N^2/t) and EV_S = EV_100 + log2(S/100), names the nearest one-third-stop f-number, and lists the equivalent shutter time at each f-number from f/1 to f/32. Given all four, checks that they agree within a tolerance in stops. Built for camera, lighting and image-generation agents that need exact reciprocal exposure arithmetic. It does not model reciprocity failure, flash, metering modes or lens transmission (T-stops), and the f-number scale is the typical third-stop series, not a lens''s marked values.
Price: 0.005 USDC on Base (x402).'
x-x402-price-usdc: '0.005'
x-x402-amount: '5000'
x-payment-info:
protocols:
- x402
price:
mode: fixed
currency: USD
amount: '0.005'
x-audience: business
x-sample-url: https://agents.writerslogic.com/api/v1/samples/exposure-calc
security:
- x402: []
- apiKey: []
requestBody:
required: true
content:
application/json:
schema:
type: object
additionalProperties: false
required: []
properties:
aperture:
type: number
description: f-number N.
minimum: 0.5
maximum: 256
shutterSeconds:
type: number
description: Exposure time t in seconds.
minimum: 1.0e-06
maximum: 3600
iso:
type: number
description: ISO speed S.
minimum: 1
maximum: 10000000
ev100:
type: number
description: Scene light as exposure value at ISO 100.
minimum: -10
maximum: 30
toleranceStops:
type: number
description: 'When all four are given: largest EV100 disagreement accepted (default 0.05).'
minimum: 0
maximum: 3
example:
aperture: 8
shutterSeconds: 0.008
iso: 100
responses:
'200':
description: Paid result with provenance
content:
application/json:
schema:
type: object
properties:
data:
type: object
properties:
status:
type: string
enum:
- pass
- fail
- unknown
- unsupported
description: 'pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass.'
missing:
type: array
items:
type: string
maxLength: 20
description: field name
maxItems: 4
description: Fields still needed (status unknown).
solvedField:
type: string
description: aperture, shutterSeconds, iso, ev100, or none when all four were given.
aperture:
type: number
description: f-number used or solved.
shutterSeconds:
type: number
description: Exact seconds.
shutterLabel:
type: string
description: Rounded display label such as 1/125; use shutterSeconds for arithmetic.
iso:
type: number
description: ISO used or solved.
evSetting:
type: number
description: log2(N^2/t) for the settings at this ISO.
ev100:
type: number
description: The same light level expressed at ISO 100.
nearestFNumber:
type: number
description: Nearest f-number on the typical one-third-stop scale.
nearestFNumberStopsOff:
type: number
description: Signed distance from that label in stops.
equivalents:
type: array
items:
type: object
description: aperture, shutterSeconds, shutterLabel at the same exposure.
maxItems: 40
witnesses:
type: array
items:
type: object
properties:
ruleId:
type: string
detail:
type: string
path:
type: string
description: JSON pointer or dotted path into the input.
offset:
type: integer
index:
type: integer
expected:
description: What the rule required.
actual:
description: What the input had.
versions:
type: object
description: Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
limits:
type: array
items:
type: string
deterministic:
type: boolean
description: 'Always true: pure code, no model.'
_provenance:
type: object
description: C2PA-aligned manifest and W3C VC 2.0 (eddsa-jcs-2022) issued by the hub DID; verify at POST /api/v1/verify-provenance
required:
- data
- _provenance
'400':
description: Invalid request (no payment consumed)
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
'401':
description: Invalid X-API-KEY
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
'402':
description: Payment required or invalid
content:
application/json:
schema:
type: object
description: x402 v2 PaymentRequired (also base64 in the PAYMENT-REQUIRED header)
properties:
x402Version:
type: integer
error:
type: string
code:
type: string
resource:
type: object
accepts:
type: array
items:
type: object
extensions:
type: object
'502':
description: Upstream failure; the payment is released or not settled
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
tags:
- Exposure Calc
components:
securitySchemes:
x402:
type: apiKey
in: header
name: PAYMENT-SIGNATURE
description: x402 v2 payment payload (base64) sent after a 402 challenge
apiKey:
type: apiKey
in: header
name: X-API-KEY