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copied!<p>Ah, problem is:</p> <blockquote> <p>If timeout is greater than 0, then it will kill the child process if it runs longer than timeout milliseconds. The child process is killed with killSignal (default: 'SIGTERM'). maxBuffer specifies the largest amount of data allowed on stdout or stderr - if this value is exceeded then the child process is killed.</p> </blockquote> <p>Source: <a href="http://nodejs.org/docs/v0.4.8/api/child_processes.html#child_process.exec" rel="noreferrer">http://nodejs.org/docs/v0.4.8/api/child_processes.html#child_process.exec</a></p> <p>So if your image is over the default buffer size of 200*1024 bytes, your image is going to be corrupted as you mentioned. I was able to get it to work with the following code:</p> <pre><code>var fs = require('fs'); var spawn = require('child_process').spawn; var util = require('util'); var output_file = fs.createWriteStream('test2.jpg', {encoding: 'binary'}); var convert = spawn('convert', ['test.jpg', '-']); convert.stdout.on('data', function(data) { output_file.write(data); }); convert.on('exit', function(code) { output_file.end(); }); </code></pre> <p>Here I used spawn to get a streamable stdout, then I used a Writeable Stream to write the data in binary format. Just tested it and was able to open the resulting <code>test2.jpg</code> image.</p> <p><strong>EDIT</strong>: Yes you can use this to send the result over HTTP. Here's an example of me downsizing an image with convert, then posting the result to the glowfoto API:</p> <pre><code>var fs = require('fs'); var http = require('http'); var util = require('util'); var spawn = require('child_process').spawn; var url = require('url'); // Technically the only reason I'm using this // is to get the XML parsed from the first call // you probably don't need this, but just in case: // // npm install xml2js var xml = require('xml2js'); var post_url; var input_filename = 'giant_image.jpg'; var output_filename = 'giant_image2.jpg'; // The general format of a multipart/form-data part looks something like: // --[boundary]\r\n // Content-Disposition: form-data; name="fieldname"\r\n // \r\n // field value function EncodeFieldPart(boundary,name,value) { var return_part = "--" + boundary + "\r\n"; return_part += "Content-Disposition: form-data; name=\"" + name + "\"\r\n\r\n"; return_part += value + "\r\n"; return return_part; } // Same as EncodeFieldPart except that it adds a filename, // as well as sets the content type (mime) for the part function EncodeFilePart(boundary,type,name,filename) { var return_part = "--" + boundary + "\r\n"; return_part += "Content-Disposition: form-data; name=\"" + name + "\"; filename=\"" + filename + "\"\r\n"; return_part += "Content-Type: " + type + "\r\n\r\n"; return return_part; } // We could use Transfer-Encoding: Chunked in the headers // but not every server supports this. Instead we're going // to build our post data, then create a buffer from it to // pass to our MakePost() function. This means you'll have // 2 copies of the post data sitting around function PreparePost() { // Just a random string I copied from a packet sniff of a mozilla post // This can be anything you want really var boundary = "---------------------------168072824752491622650073"; var post_data = ''; post_data += EncodeFieldPart(boundary, 'type', 'file'); post_data += EncodeFieldPart(boundary, 'thumbnail', '400'); post_data += EncodeFilePart(boundary, 'image/jpeg', 'image', output_filename); fs.readFile(output_filename, 'binary', function(err,data){ post_data += data; // This terminates our multi-part data post_data += "\r\n--" + boundary + "--"; // We need to have our network transfer in binary // Buffer is a global object MakePost(new Buffer(post_data, 'binary')); }); } function MakePost(post_data) { var parsed_url = url.parse(post_url); var post_options = { host: parsed_url.hostname, port: '80', path: parsed_url.pathname, method: 'POST', headers : { 'Content-Type' : 'multipart/form-data; boundary=---------------------------168072824752491622650073', 'Content-Length' : post_data.length } }; var post_request = http.request(post_options, function(response){ response.setEncoding('utf8'); response.on('data', function(chunk){ console.log(chunk); }); }); post_request.write(post_data); post_request.end(); } // Glowfoto first makes you get the url of the server // to upload function GetServerURL() { var response = ''; var post_options = { host: 'www.glowfoto.com', port: '80', path: '/getserverxml.php' }; var post_req = http.request(post_options, function(res) { res.setEncoding('utf8'); // Here we buildup the xml res.on('data', function (chunk) { response += chunk; }); // When we're done, we parse the xml // Could probably just do string manipulation instead, // but just to be safe res.on('end', function(){ var parser = new xml.Parser(); parser.addListener('end', function(result){ // Grab the uploadform element value and prepare our post post_url = result.uploadform; PreparePost(); }); // This parses an XML string into a JS object var xml_object = parser.parseString(response); }); }); post_req.end(); } // We use spawn here to get a streaming stdout // This will use imagemagick to downsize the full image to 30% var convert = spawn('convert', ['-resize', '30%', input_filename, '-']); // Create a binary write stream for the resulting file var output_file = fs.createWriteStream(output_filename, {encoding: 'binary'}); // This just writes to the file and builds the data convert.stdout.on('data', function(data){ output_file.write(data); }); // When the process is done, we close off the file stream // Then trigger off our POST code convert.on('exit', function(code){ output_file.end(); GetServerURL(); }); </code></pre> <p>Sample result:</p> <pre><code>$ node test.js <?xml version="1.0" encoding="utf-8"?> <upload> <thumburl>http://img4.glowfoto.com/images/2011/05/29-0939312591T.jpg</thumburl> <imageurl>http://www.glowfoto.com/static_image/29-093931L/2591/jpg/05/2011/img4/glowfoto</imageurl> <codes>http://www.glowfoto.com/getcode.php?srv=img4&amp;img=29-093931L&amp;t=jpg&amp;rand=2591&amp;m=05&amp;y=2011</codes> </upload> </code></pre>

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