I'm implementing some features to perform OCR on images and until now everything is going very well. The problem is; the OCR works fine if the image is in the correct rotation, if it is upside down or in a 90 ° rotation the OCR ends up picking up texts that I would call garbage because they would not make sense when working with them. >
Imagine this image: 
See that she's upside down. Doing her spin is quiet, but how do you check if she's upside down so she can spin it?
The latest OCR technologies have auto-rotate settings. The Computer Vision API contains this setting through the detectOrientation property. According to the tests I did this property by default is true, that is, when performing the image verification the API already rotates the image to capture the information.
Assigning parameters to the request:
var requestParameters = "language=pt&detectOrientation=true";
Using the image below:
ResultwithdetectOrientationequaltotrue
{"language": "pt",
"textAngle": 0.0,
"orientation": "Down",
"regions": [{
"boundingBox": "5,14,503,202",
"lines": [{
"boundingBox": "9,14,498,40",
"words": [{
"boundingBox": "9,14,27,32",
"text": "If"
}, {
"boundingBox": "46,22,59,32",
"text": "you"
}, {
"boundingBox": "118,22,59,23",
"text": "can"
}, {
"boundingBox": "191,15,73,31",
"text": "read"
}, {
"boundingBox": "276,15,59,31",
"text": "this"
}, {
"boundingBox": "348,15,70,31",
"text": "with"
}, {
"boundingBox": "431,22,76,31",
"text": "easy"
}]
}, {
"boundingBox": "5,70,503,37",
"words": [{
"boundingBox": "5,77,59,30",
"text": "you"
}, {
"boundingBox": "79,77,52,24",
"text": "are"
}, {
"boundingBox": "143,70,131,31",
"text": "twisted!"
}, {
"boundingBox": "296,70,67,32",
"text": "And"
}, {
"boundingBox": "378,70,79,32",
"text": "have"
}, {
"boundingBox": "470,77,38,24",
"text": "an"
}]
}, {
"boundingBox": "10,124,493,34",
"words": [{
"boundingBox": "10,132,156,26",
"text": "awesome"
}, {
"boundingBox": "179,125,105,33",
"text": "talent!"
}, {
"boundingBox": "310,124,71,32",
"text": "This"
}, {
"boundingBox": "391,126,27,30",
"text": "is"
}, {
"boundingBox": "432,125,71,31",
"text": "both"
}]
}, {
"boundingBox": "15,175,485,41",
"words": [{
"boundingBox": "15,175,175,34",
"text": "backwards"
}, {
"boundingBox": "204,178,59,32",
"text": "and"
}, {
"boundingBox": "278,179,108,37",
"text": "upside"
}, {
"boundingBox": "399,179,101,30",
"text": "down!"
}]
}]
}]
}
Now the same test set the property value to false
var requestParameters = "language=pt&detectOrientation=false";
Result with detectOrientation equal to false
{
"language": "pt",
"textAngle": 0.0,
"orientation": "NotDetected",
"regions": [{
"boundingBox": "4,15,503,202",
"lines": [{
"boundingBox": "12,15,485,41",
"words": [{
"boundingBox": "12,22,101,30",
"text": "-iUMOP"
}, {
"boundingBox": "126,15,108,37",
"text": "ap!Sdn"
}, {
"boundingBox": "249,21,59,32",
"text": "pue"
}, {
"boundingBox": "322,22,175,34",
"text": "sp]ewpeq"
}]
}, {
"boundingBox": "9,73,493,33",
"words": [{
"boundingBox": "9,75,71,31",
"text": "l.poq"
}, {
"boundingBox": "94,75,27,30",
"text": "s!"
}, {
"boundingBox": "346,73,156,26",
"text": "awosame"
}]
}, {
"boundingBox": "4,124,503,37",
"words": [{
"boundingBox": "4,130,38,24",
"text": "ue"
}, {
"boundingBox": "149,129,67,32",
"text": "puv"
}, {
"boundingBox": "238,130,131,31",
"text": "ipaF!Ma"
}, {
"boundingBox": "381,130,52,24",
"text": "ae"
}, {
"boundingBox": "448,124,59,30",
"text": "noÁ"
}]
}, {
"boundingBox": "5,177,498,40",
"words": [{
"boundingBox": "5,178,76,31",
"text": "Ásea"
}, {
"boundingBox": "94,185,70,31",
"text": "qa!M"
}, {
"boundingBox": "248,185,73,31",
"text": "pea]"
}, {
"boundingBox": "335,186,59,23",
"text": "ueo"
}, {
"boundingBox": "407,177,59,32",
"text": "noÁ"
}, {
"boundingBox": "476,185,27,32",
"text": "JI"
}]
}]
}]
}
Here you can view properties and perform tests using Ocp-Apim-Subscription-Key .
I used the example provided here for my test . .
I also did the test with your image, in my opinion it worked as expected, but the distribution of the texts does not help. (I did not put the entire Json because it passed the character limit of a response)
{
"language": "pt",
"textAngle": 0.0,
"orientation": "Down",
"regions": [{
"boundingBox": "1113,32,57,20",
"lines": [{
"boundingBox": "1113,32,57,20",
"words": [{
"boundingBox": "1113,32,57,20",
"text": "-Dep-"
}]
}]
}, {
"boundingBox": "198,59,228,18",
"lines": [{
"boundingBox": "198,59,228,18",
"words": [{
"boundingBox": "198,61,47,16",
"text": "Nome"
}, {
"boundingBox": "257,60,24,17",
"text": "do"
}, {
"boundingBox": "296,59,130,18",
"text": "Funcionario"
}]
}]
}, {
"boundingBox": "572,58,129,22",
"lines": [{
"boundingBox": "572,58,129,22",
"words": [{
"boundingBox": "572,58,129,22",
"text": "Cargo-Nivel"
}]
}]
}, {
"boundingBox": "777,33,319,94",
"lines": [{
"boundingBox": "1017,33,58,20",
"words": [{
"boundingBox": "1017,33,58,20",
"text": "Carga"
}]
}, {
"boundingBox": "1005,57,82,17",
"words": [{
"boundingBox": "1005,57,82,17",
"text": "Horaria"
}]
}, {
"boundingBox": "777,107,319,20",
"words": [{
"boundingBox": "777,108,34,17",
"text": "054"
}, {
"boundingBox": "825,107,190,18",
"text": "GLES-L.4.620-FMS"
}, {
"boundingBox": "1030,107,66,20",
"text": "111,11"
}]
}]
}, {
"boundingBox": "1363,29,106,47",
"lines": [{
"boundingBox": "1364,29,105,18",
"words": [{
"boundingBox": "1364,29,57,18",
"text": "Total"
}, {
"boundingBox": "1435,29,34,17",
"text": "das"
}]
}, {
"boundingBox": "1363,56,106,20",
"words": [{
"boundingBox": "1363,56,106,20",
"text": "Vantagens"
}]
}]
}, {
"boundingBox": "66,60,1430,1191",
"lines": [{
"boundingBox": "66,60,106,18",
"words": [{
"boundingBox": "66,60,106,18",
"text": "Matricula"
}]
}, {
"boundingBox": "1401,180,70,21",
"words": [{
"boundingBox": "1401,180,70,21",
"text": "302,36"
}]
}]
}
If the image contains the EXIF standard you can identify and rotate if necessary.
EXIF (Exchangeable Image File Format) is a specified default and followed by manufacturers of digital cameras that record information on the technical characteristics of the capture of a certain image in JPG or TIFF format.
Taking an image that contains EXIF through a URL:
WebClient wc = new System.Net.WebClient();
byte[] bytes = wc.DownloadData("https://github.com/recurser/exif-orientation-examples/blob/master/Portrait_3.jpg?raw=true");
MemoryStream ms = new MemoryStream(bytes);
System.Drawing.Image img = System.Drawing.Image.FromStream(ms);
Picking up and rotating:
int idOrientacao = 0x0112; // id da propridade que contem a orientação, 247 hex.
if (img.PropertyIdList.Contains(idOrientacao)) { // verificando se a imagem possui a propridade que contem a informação da orientação, imagens sem EXIF não possuem.
int valorOrientacao = (int) img.GetPropertyItem(idOrientacao).Value[0]; // valor que representa a orientação da imagem, tabela explicava logo abaixo.
switch (valorOrientacao) {
case 1:
// Não precisa rotacionar
break;
case 2:
img.RotateFlip(RotateFlipType.RotateNoneFlipX);
break;
case 3:
img.RotateFlip(RotateFlipType.Rotate180FlipNone);
break;
case 4:
img.RotateFlip(RotateFlipType.Rotate180FlipX);
break;
case 5:
img.RotateFlip(RotateFlipType.Rotate90FlipX);
break;
case 6:
img.RotateFlip(RotateFlipType.Rotate90FlipNone);
break;
case 7:
img.RotateFlip(RotateFlipType.Rotate270FlipX);
break;
case 8:
img.RotateFlip(RotateFlipType.Rotate270FlipNone);
break;
}
// Aqui você remove a propridade que contem a orientação, já que ela foi alterada.
img.RemovePropertyItem(idOrientacao);
}
Possible values for the variable valorOrientação : documentation here .
Rotation options: here documentation