How to Get Information About an Image using C/C++

Before we make any significant programmatic edits to an image, we first need to retrieve the image’s metadata so we can understand what we’re changing. Using the below code, you can take advantage of a free API that quickly retrieves metadata from an input image (supports 100+ image formats with multipart/form-data input) and returns it in an organized list.

To structure your API call using the C/C++ examples below, first install libcurl in your project:

libcurl/7.75.0

Then include the below code, and supply a free-tier API key to authorize your request (this will allow up to 800 API calls per month with no commitment):

CURL *curl;
CURLcode res;
curl = curl_easy_init();
if(curl) {
     curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "POST");
     curl_easy_setopt(curl, CURLOPT_URL, "https://api.cloudmersive.com/convert/image/get-info");
     curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
     curl_easy_setopt(curl, CURLOPT_DEFAULT_PROTOCOL, "https");
     struct curl_slist *headers = NULL;
     headers = curl_slist_append(headers, "Content-Type: multipart/form-data");
     headers = curl_slist_append(headers, "Apikey: YOUR-API-KEY-HERE");
     curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
     curl_mime *mime;
     curl_mimepart *part;
     mime = curl_mime_init(curl);
     part = curl_mime_addpart(mime);
     curl_mime_name(part, "inputFile");
     curl_mime_filedata(part, "/path/to/file");
     curl_easy_setopt(curl, CURLOPT_MIMEPOST, mime);
     res = curl_easy_perform(curl);
     curl_mime_free(mime);
}
curl_easy_cleanup(curl);

Easy, right? You’ll receive as much of the below information as the image file allows:

{
  "Successful": true,
  "ColorSpace": "string",
  "ColorType": "string",
  "Width": 0,
  "Height": 0,
  "CompressionLevel": 0,
  "ImageHashSignature": "string",
  "HasTransparency": true,
  "MimeType": "string",
  "ImageFormat": "string",
  "DPIUnit": "string",
  "DPI": 0,
  "ColorCount": 0,
  "BitDepth": 0,
  "Comment": "string",
  "ExifProfileName": "string",
  "ExifValues": [
    {
      "Tag": "string",
      "DataType": "string",
      "DataValue": "string"
    }
  ]
}