JS Client-Side Exif Orientation: Rotate and Mirror JPEG Images

Question

Digital camera photos are often saved as JPEG with an EXIF \"orientation\" tag. To display correctly, images need to be rotated/mirrored depending on which orientation is se

Answer 1

In addition to @fareed namrouti's answer,

This should be used if the image has to be browsed from a file input element

<input type="file" name="file" id="file-input"><br/>
image after transform: <br/>
<div id="container"></div>

<script>
    document.getElementById('file-input').onchange = function (e) {
        var image = e.target.files[0];
        window.loadImage(image, function (img) {
            if (img.type === "error") {
                console.log("couldn't load image:", img);
            } else {
                window.EXIF.getData(image, function () {
                    console.log("load image done!");
                    var orientation = window.EXIF.getTag(this, "Orientation");
                    var canvas = window.loadImage.scale(img,
                        {orientation: orientation || 0, canvas: true, maxWidth: 200});
                    document.getElementById("container").appendChild(canvas);
                    // or using jquery $("#container").append(canvas);
                });
            }
        });
    };
</script>

Answer 2

Mederr's context transform works perfectly. If you need to extract orientation only use this function - you don't need any EXIF-reading libs. Below is a function for re-setting orientation in base64 image. Here's a fiddle for it. I've also prepared a fiddle with orientation extraction demo.

function resetOrientation(srcBase64, srcOrientation, callback) {
  var img = new Image();    

  img.onload = function() {
    var width = img.width,
        height = img.height,
        canvas = document.createElement('canvas'),
        ctx = canvas.getContext("2d");

    // set proper canvas dimensions before transform & export
    if (4 < srcOrientation && srcOrientation < 9) {
      canvas.width = height;
      canvas.height = width;
    } else {
      canvas.width = width;
      canvas.height = height;
    }

    // transform context before drawing image
    switch (srcOrientation) {
      case 2: ctx.transform(-1, 0, 0, 1, width, 0); break;
      case 3: ctx.transform(-1, 0, 0, -1, width, height); break;
      case 4: ctx.transform(1, 0, 0, -1, 0, height); break;
      case 5: ctx.transform(0, 1, 1, 0, 0, 0); break;
      case 6: ctx.transform(0, 1, -1, 0, height, 0); break;
      case 7: ctx.transform(0, -1, -1, 0, height, width); break;
      case 8: ctx.transform(0, -1, 1, 0, 0, width); break;
      default: break;
    }

    // draw image
    ctx.drawImage(img, 0, 0);

    // export base64
    callback(canvas.toDataURL());
  };

  img.src = srcBase64;
};

Answer 3

I am using mixed solution (php+css).

Containers are needed for:

• div.imgCont2 container needed to rotate;
• div.imgCont1 container needed to zoomOut - width:150%;
• div.imgCont container needed for scrollbars, when image is zoomOut.

.

<?php
    $image_url = 'your image url.jpg';
    $exif = @exif_read_data($image_url,0,true);
    $orientation = @$exif['IFD0']['Orientation'];
?>

<style>
.imgCont{
    width:100%;
    overflow:auto;
}
.imgCont2[data-orientation="8"]{
    transform:rotate(270deg);
    margin:15% 0;
}
.imgCont2[data-orientation="6"]{
    transform:rotate(90deg);
    margin:15% 0;
}
.imgCont2[data-orientation="3"]{
    transform:rotate(180deg);
}
img{
    width:100%;
}
</style>

<div class="imgCont">
  <div class="imgCont1">
    <div class="imgCont2" data-orientation="<?php echo($orientation) ?>">
      <img src="<?php echo($image_url) ?>">
    </div>
  </div>
</div>

Answer 4

I created a class wrapped in an ES6 module that solves exactly this.

It's 103 lines, no dependencies, and fairly nicely structured and documented, meant to be easy to modify/reuse.

Handles all 8 possible orientations, and is Promise-based.

Here you go, hope this still helps someone: https://gist.github.com/vdavid/3f9b66b60f52204317a4cc0e77097913

Answer 5

For those who have a file from an input control, don't know what its orientation is, are a bit lazy and don't want to include a large library below is the code provided by @WunderBart melded with the answer he links to (https://stackoverflow.com/a/32490603) that finds the orientation.

function getDataUrl(file, callback2) {
        var callback = function (srcOrientation) {
            var reader2 = new FileReader();
            reader2.onload = function (e) {
                var srcBase64 = e.target.result;
                var img = new Image();

                img.onload = function () {
                    var width = img.width,
                        height = img.height,
                        canvas = document.createElement('canvas'),
                        ctx = canvas.getContext("2d");

                    // set proper canvas dimensions before transform & export
                    if (4 < srcOrientation && srcOrientation < 9) {
                        canvas.width = height;
                        canvas.height = width;
                    } else {
                        canvas.width = width;
                        canvas.height = height;
                    }

                    // transform context before drawing image
                    switch (srcOrientation) {
                        case 2: ctx.transform(-1, 0, 0, 1, width, 0); break;
                        case 3: ctx.transform(-1, 0, 0, -1, width, height); break;
                        case 4: ctx.transform(1, 0, 0, -1, 0, height); break;
                        case 5: ctx.transform(0, 1, 1, 0, 0, 0); break;
                        case 6: ctx.transform(0, 1, -1, 0, height, 0); break;
                        case 7: ctx.transform(0, -1, -1, 0, height, width); break;
                        case 8: ctx.transform(0, -1, 1, 0, 0, width); break;
                        default: break;
                    }

                    // draw image
                    ctx.drawImage(img, 0, 0);

                    // export base64
                    callback2(canvas.toDataURL());
                };

                img.src = srcBase64;
            }

            reader2.readAsDataURL(file);
        }

        var reader = new FileReader();
        reader.onload = function (e) {

            var view = new DataView(e.target.result);
            if (view.getUint16(0, false) != 0xFFD8) return callback(-2);
            var length = view.byteLength, offset = 2;
            while (offset < length) {
                var marker = view.getUint16(offset, false);
                offset += 2;
                if (marker == 0xFFE1) {
                    if (view.getUint32(offset += 2, false) != 0x45786966) return callback(-1);
                    var little = view.getUint16(offset += 6, false) == 0x4949;
                    offset += view.getUint32(offset + 4, little);
                    var tags = view.getUint16(offset, little);
                    offset += 2;
                    for (var i = 0; i < tags; i++)
                        if (view.getUint16(offset + (i * 12), little) == 0x0112)
                            return callback(view.getUint16(offset + (i * 12) + 8, little));
                }
                else if ((marker & 0xFF00) != 0xFF00) break;
                else offset += view.getUint16(offset, false);
            }
            return callback(-1);
        };
        reader.readAsArrayBuffer(file);
    }

which can easily be called like such

getDataUrl(input.files[0], function (imgBase64) {
      vm.user.BioPhoto = imgBase64;
});

Answer 6

Wunderbart's post worked for me combined with statler's improvements. Adding a few more comments and syntax cleanup, and also passing back the orientation value and I have the following code feel free to use. Just call readImageFile() function below and you get back the transformed image and the original orientation.

const JpegOrientation = [
    "NOT_JPEG",
    "NORMAL",
    "FLIP-HORIZ",
    "ROT180",
    "FLIP-HORIZ-ROT180",
    "FLIP-HORIZ-ROT270",
    "ROT270",
    "FLIP-HORIZ-ROT90",
    "ROT90"
];


//Provided a image file, determines the orientation of the file based on the EXIF information.
//Calls the "callback" function with an index into the JpegOrientation array. 
//If the image is not a JPEG, returns 0. If  the orientation value cannot be read (corrupted file?) return -1.
function getOrientation(file, callback) {
    
    const reader = new FileReader();
    reader.onload = (e) => {

        const view = new DataView(e.target.result);
        
        if (view.getUint16(0, false) !== 0xFFD8) {
            return callback(0);  //NOT A JPEG FILE
        }
        
        const length = view.byteLength;
        let offset = 2;
        while (offset < length) {
            
            if (view.getUint16(offset+2, false) <= 8)   //unknown?
                return callback(-1);
            
            const marker = view.getUint16(offset, false);
            offset += 2;
            if (marker === 0xFFE1) {
                
                if (view.getUint32(offset += 2, false) !== 0x45786966) 
                    return callback(-1); //unknown?
                

                const little = view.getUint16(offset += 6, false) === 0x4949;
                offset += view.getUint32(offset + 4, little);
                const tags = view.getUint16(offset, little);
                offset += 2;
                for (var i = 0; i < tags; i++) {
                    if (view.getUint16(offset + (i * 12), little) === 0x0112) {
                        return callback(view.getUint16(offset + (i * 12) + 8, little));   //found orientation code
                    }
                }
            }
            else if ((marker & 0xFF00) !== 0xFF00) {
                break;
            }
            else { 
                offset += view.getUint16(offset, false);
            }
        }
        
        return callback(-1); //unknown?
    };
    reader.readAsArrayBuffer(file);
}

//Takes a jpeg image file as base64 and transforms it back to original, providing the
//transformed image in callback.  If the image is not a jpeg or is already in normal orientation,
//just calls the callback directly with the source.
//Set type to the desired output type if transformed, default is image/jpeg for speed.
function resetOrientation(srcBase64, srcOrientation, callback, type = "image/jpeg") {
    
    if (srcOrientation <= 1) {  //no transform needed
        callback(srcBase64);
        return;
    }
    
    const img = new Image();    

    img.onload = () => {
        const width = img.width;
        const height = img.height;
        const canvas = document.createElement('canvas');
        const ctx = canvas.getContext("2d");

        // set proper canvas dimensions before transform & export
        if (4 < srcOrientation && srcOrientation < 9) {
            canvas.width = height;
            canvas.height = width;
        } else {
            canvas.width = width;
            canvas.height = height;
        }

        // transform context before drawing image
        switch (srcOrientation) {
              
              //case 1: normal, no transform needed
              
              case 2:  
                  ctx.transform(-1, 0, 0, 1, width, 0); 
                  break;
              case 3:
                  ctx.transform(-1, 0, 0, -1, width, height); 
                  break;
              case 4: 
                  ctx.transform(1, 0, 0, -1, 0, height); 
                  break;
              case 5: 
                  ctx.transform(0, 1, 1, 0, 0, 0); 
                  break;
              case 6: 
                  ctx.transform(0, 1, -1, 0, height, 0); 
                  break;
              case 7: 
                  ctx.transform(0, -1, -1, 0, height, width); 
                  break;
              case 8: 
                  ctx.transform(0, -1, 1, 0, 0, width); 
                  break;
              default: 
                  break;
        }

        // draw image
        ctx.drawImage(img, 0, 0);

        //export base64
        callback(canvas.toDataURL(type), srcOrientation);
    };

    img.src = srcBase64;
};


//Read an image file, providing the returned data to callback. If the image is jpeg
//and is transformed according to EXIF info, transform it first.
//The callback function receives the image data and the orientation value (index into JpegOrientation)
export function readImageFile(file, callback) {

    getOrientation(file, (orientation) => {

        console.log("Read file \"" + file.name + "\" with orientation: " + JpegOrientation[orientation]);

        const reader = new FileReader();
        reader.onload = () => {  //when reading complete

            const img = reader.result;
            resetOrientation(img, orientation, callback);
        };
        reader.readAsDataURL(file);  //start read
        
    });
}