Convert Image Format API
What this endpoint does: The PDF4me Convert Image Format REST API converts images between JPG, PNG, WebP, BMP, GIF, and TIFF formats in a single POST call. Send your source image as a Base64-encoded string, specify the current format and the target format, and receive back the converted image — also as Base64. Use it to standardise image formats across a processing pipeline, convert legacy BMP or TIFF files for web delivery, or prepare images before running them through the Compress Image endpoint.
Authenticating Your API Request
Every PDF4me REST API call must include your API key in the Authorization header. Obtain your key from the developer dashboard and keep it out of client-side code.
Important Facts You Should Not Miss
docName, docContent, CurrentImageFormat, and NewImageFormat must all be present. A missing format parameter causes the API to return a 400 error. Always provide both format fields explicitly — do not assume the API will infer the source format from the file extension in docName.
The API uses CurrentImageFormat to select the correct decoding codec. If you send a PNG file but set CurrentImageFormat to JPG, decoding fails with a format error. Read the real format from your source file MIME type or binary header — never derive it solely from the filename extension, which can be wrong.
JPG does not support an alpha channel. Transparent areas in a PNG or GIF source are filled with white (or a default background) during JPG conversion. If your image has a transparent background — logos, cut-out product photos, icons — convert to PNG, GIF, or BMP instead of JPG to preserve the transparency.
REST API Endpoint
| Method | Endpoint |
|---|---|
| POST | /api/v2/ConvertImageFormat |
Base URL: https://api.pdf4me.com
Parameters
⚠️ All four parameters are required. The API returns an error if any field is missing.
| Parameter | Required | Type | What it does | Example |
|---|---|---|---|---|
| docName | Required | String | Filename of the source image including the file extension. Used for output file naming. Should reflect the actual format of the source file. | company-logo.png |
| docContent | Required | Base64 | The complete source image file encoded as a Base64 string. Maximum file size: 50 MB. Do not include a data URL prefix — pass the raw Base64 string only. | iVBORw0KGgoAAAANSUhEUg... |
| CurrentImageFormat | Required | Enum | The actual format of the source image in docContent. Must match exactly. Accepted values: BMP · GIF · JPG · PNG · TIFF | PNG |
| NewImageFormat | Required | Enum | The target format for the converted output image. Accepted values: BMP · GIF · JPG · PNG · TIFF | JPG |
Output Fields
| Field | Type | Description |
|---|---|---|
| File Content | Base64 | The converted image encoded as Base64. Decode to binary and save with the correct new file extension. |
| File Name | String | Filename of the converted output image. |
Request Example
Headers
Content-Type: application/json
Authorization: YOUR_API_KEY
JSON Payload
{
"docName": "company-logo.png",
"docContent": "iVBORw0KGgoAAAANSUhEUg...",
"CurrentImageFormat": "PNG",
"NewImageFormat": "JPG"
}
Response
{
"File Content": "BASE64_CONVERTED_IMAGE_DATA",
"File Name": "company-logo.jpg"
}
Code Samples
Common Use Cases
Marketing teams often accumulate mixed BMP, TIFF, and GIF files from various sources. Convert them all to PNG in a batch processing loop — PNG gives lossless quality and wide browser support, making it the safest default web format for logos and graphics.
Studio photographs are typically delivered as TIFF (50–200 MB each). Convert to JPG before uploading to your e-commerce platform or CDN to reduce storage costs by 80–90%. Pair with the Compress Image endpoint for a complete optimisation pipeline.
WebP images are 25–35% smaller than equivalent JPGs and supported by all modern browsers. Convert JPG or PNG assets to WebP to improve Core Web Vitals scores. Serve WebP with a JPG fallback using HTML picture elements.
Frequently Asked Questions
▶ What image formats does the Convert Image Format API support?
The API supports BMP, GIF, JPG, PNG, and TIFF as both input (CurrentImageFormat) and output (NewImageFormat). These five formats cover the most common image types used in enterprise and web workflows.
▶ Does CurrentImageFormat need to match the actual binary format of docContent?
Yes — always. The API uses CurrentImageFormat to select the correct decoding codec. A mismatch between the actual binary format and CurrentImageFormat causes a decoding failure. Read the real format from your file's MIME type or binary signature, not just the filename extension.
▶ How does PNG-to-JPG conversion handle transparency?
JPG does not support an alpha channel. Transparent areas in a PNG source are replaced with a solid background colour (typically white) during conversion. If preserving transparency matters — logos, product cut-outs, icons — convert to PNG, GIF, or BMP instead of JPG.
▶ Can I convert and compress an image in the same API call?
No — Convert Image Format only changes the format. To also compress, call Convert Image Format first to get the target format, then pass the result's File Content to the Compress Image endpoint with your chosen compression level. Chain both calls in your application.
▶ What is the maximum file size accepted by this endpoint?
Up to 50 MB. For best performance keep images under 10 MB. Note that format conversion can change file size — converting a PNG to JPG typically reduces size, while converting JPG to TIFF may increase it significantly.