read-ihdr
Extract IHDR metadata from images to retrieve width, height, and other critical attributes. Supports inputs as paths, URLs, base64 data, or buffers for flexible integration.
Instructions
Read IHDR metadata from an image
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| image | Yes |
Implementation Reference
- src/tools/index.ts:154-170 (handler)Core handler logic for executing the read-ihdr tool. Loads image buffer, configures exifr.parse for IHDR segment via buildSegmentOptions('IHDR'), extracts and returns IHDR metadata or error.async (args, extra) => { try { const { image } = args; const buf = await loadImage(image); const opts = buildSegmentOptions(segment); const meta = await exifr.parse(buf, opts); const segmentKey = segment.toLowerCase(); if (!meta || !meta[segmentKey]) { return createErrorResponse(`No ${segment} metadata found in image`); } return createSuccessResponse(meta); } catch (error) { return createErrorResponse(`Error reading ${segment} data: ${error instanceof Error ? error.message : String(error)}`); } }
- src/tools/index.ts:148-173 (registration)Registration of read-ihdr tool using server.tool in a forEach loop over segmentTools (which includes {name: 'read-ihdr', segment: 'IHDR'} at line 145). Includes inline schema and handler.segmentTools.forEach(({ name, segment }) => { const segmentTool = server.tool(name, `Read ${segment} metadata from an image`, { image: ImageSourceSchema }, async (args, extra) => { try { const { image } = args; const buf = await loadImage(image); const opts = buildSegmentOptions(segment); const meta = await exifr.parse(buf, opts); const segmentKey = segment.toLowerCase(); if (!meta || !meta[segmentKey]) { return createErrorResponse(`No ${segment} metadata found in image`); } return createSuccessResponse(meta); } catch (error) { return createErrorResponse(`Error reading ${segment} data: ${error instanceof Error ? error.message : String(error)}`); } } ); tools[name] = segmentTool; });
- src/tools/index.ts:54-60 (schema)Zod schema defining the 'image' input parameter for read-ihdr tool and other image tools.const ImageSourceSchema = z.object({ kind: z.enum(['path', 'url', 'base64', 'buffer']), path: z.string().optional(), url: z.string().optional(), data: z.string().optional(), buffer: z.string().optional() });
- src/tools/segments.ts:114-128 (helper)Helper function buildSegmentOptions called with 'IHDR' to create exifr options object enabling only ihdr: true parsing.export function buildSegmentOptions(segment: 'ICC' | 'IPTC' | 'JFIF' | 'IHDR'): ExifrOptions { const options: ExifrOptions = { tiff: false, xmp: false, icc: false, iptc: false, jfif: false, ihdr: false, }; const key = segment.toLowerCase() as 'icc' | 'iptc' | 'jfif' | 'ihdr'; options[key] = true; return options; }
- src/tools/loaders.ts:11-72 (helper)Helper function loadImage converts ImageSource input to image buffer for exifr.parse.export async function loadImage(src: ImageSourceType): Promise<Buffer | Uint8Array> { try { switch (src.kind) { case 'path': if (!src.path) { throw new Error('Path is required for kind="path"'); } return await fs.promises.readFile(src.path); case 'url': if (!src.url) { throw new Error('URL is required for kind="url"'); } if (src.url.startsWith('file://')) { // Handle file:// URLs by converting to filesystem path const filePath = fileURLToPath(src.url); return await fs.promises.readFile(filePath); } else { // Handle HTTP/HTTPS URLs const response = await fetch(src.url); if (!response.ok) { throw new Error(`Failed to fetch URL: ${response.status} ${response.statusText}`); } return new Uint8Array(await response.arrayBuffer()); } case 'base64': if (!src.data) { throw new Error('Data is required for kind="base64"'); } // Check for potential oversized base64 string (>30MB) if (src.data.length > 40000000) { // ~30MB in base64 throw new Error('PayloadTooLarge: Base64 data exceeds 30MB limit'); } // Handle data URIs or raw base64 if (src.data.startsWith('data:')) { const base64Data = src.data.split(',')[1]; return Buffer.from(base64Data, 'base64'); } else { return Buffer.from(src.data, 'base64'); } case 'buffer': if (!src.buffer) { throw new Error('Buffer is required for kind="buffer"'); } return Buffer.from(src.buffer, 'base64'); default: // This should never happen due to type constraints, but TypeScript needs it throw new Error(`Unsupported image source kind: ${(src as any).kind}`); } } catch (error) { if (error instanceof Error) { throw new Error(`Failed to load image: ${error.message}`); } throw error; } }