Image crop and comparision - php

Question

When i submit a new image to database which is extracted from pdf,it should be cropped image of original image. If the image already exists in database, than image should not be inserted and if its not inserted,i have to generate an identification value for that.
The identification value will also be inserted to the same table as of image.
There are keys involved. table page have the following identies
pid,qid,pidentifierval,image
$record = array('pid' => "NULL",
'qid' => $qid,
'pidentifierval' => $pid,
'image' => $crop,
'rotation' => 0);
function newquestionnaire($filename,$desc = "",$type="pngmono"){
global $db;
if ($desc == "") $desc = $filename;
//generate temp file
$tmp = tempnam(TEMPORARY_DIRECTORY, "FORM");
//print "Creating PNG files<br/>";
//use ghostscript to convert to PNG
exec(GS_BIN . " -sDEVICE=$type -r300 -sOutputFile=\"$tmp\"%d.png -dNOPAUSE -dBATCH \"$filename\"");
//add to questionnaire table
//
//create form entry in DB
//
$db->StartTrans();
$sql = "INSERT INTO questionnaires (qid,description,sheets)
VALUES (NULL,'$desc',0)";
$db->Execute($sql);
$qid = $db->Insert_Id();
//Number of imported pages
$pages = 0;
//read pages from 1 to n - stop when n does not exist
$n = 1;
$file = $tmp . $n . ".png";
while (file_exists($file))
{
$data = file_get_contents($file);
$images = split_scanning($data);
unset($image);
unset($data);
foreach($images as $data)
{
//header Cropped Function
// Original image
$filename = $data;
// Get dimensions of the original image
list($current_width, $current_height) = getimagesize($filename);
// The x and y coordinates on the original image where we
// will begin cropping the image
$left = 50;
$top = 50;
// This will be the final size of the image (e.g. how many pixels
// left and down we will be going)
$crop_width = 200;
$crop_height = 200;
// Resample the image
$canvas = imagecreatetruecolor($crop_width, $crop_height);
$current_image = imagecreatefromjpeg($filename);
imagecopy($canvas, $current_image, 0, 0, $left, $top, $current_width, $current_height);
$crop = imagepng($canvas, $filename, 100);
//check for header Cropped Image
what function should i made here ?
$pid = $pid.$pages;
if ($pid)
{
$pages++;
$record = defaultpage($qid,$pid,$crop);
$db->AutoExecute('pages',$record,'INSERT');
}
else
print T_("INVALID - IGNORING BLANK PAGE");
unset($data);
unset($crop);
i am confused here,that how should i check and compare if the image exists in the database or not. Please help

Answer 1

For cropping the image
i have found a solution
$data = '1.png';
list($current_width, $current_height) = getimagesize($data);
// The x and y co-ordinates on the original image where we will begin cropping the image
$left = 1100;
$top = 30;
// final size of image
$crop_width = 200;
$crop_height = 200;
//Resample the Image
$canvas = imagecreatefromtruecolor($crop_width, $crop_height);
$current_image = imagecreatefrompng($data);
imagecopy($canvas, $current_image, 0, 0, $left, $top, $current_width, $current_height);
imagepng($canvas, $data, 100);
For comparing two images
array image_compare(mixed $image1, mixed $image2, int $RTolerance, int $GTolerance, int $BTolerance, int $WarningTolerance, int $ErrorTolerance)
Parameters
image1
- A string containing the path to the image, or a resource of an image already created by GD Library. This is the first image to be compared.
image2
- A string containing the path to the second image, or a resource of the second image already created by GD Library. This will be the second image to be compared.
RTolerance, GTolerance, BTolerance (0-255)
- Specifies the maximum deviation for the red, green, or blue (respectively) channel before throwing a flag.
WarningTolerance (0-100)
- Percentage of channel differences before warning returned.
ErrorTolerance (0-100)
- Percentage of channel differences before error (flag) returned.
Return Values
An array will be returned with the following information:
PixelsByColors
- Pixel quantity * 3 (for each of R,G, and B channels).
PixelsOutOfSpec
- (If a pixel varies outside of xTolerance, for each red, green, and blue. Where x = R/G/B) If any channel exceeds the threshhold, this number is incremented.
PercentDifference
- The percentage of difference comparing PixelsOutOfSpec to PixelsByColors
WarningLevel and ErrorLevel
- If the percentage was large enough to trigger either the specified warning, or error level.
For comparison i have to work, i am thinking to use array.Using Select query for
getting images from the database,using while loop and fetching the result in array,calling array keys for the image to be stored in variable and using if else condition in the compare function above will work i think. What you people think ?

Answer 2

For image comparision, No Scanned image can be 100 percent accurate, so image comparision is not so easy. It is quite hectic task.
After a Lot of Research and work, I came to a point that if it is 100 percent necessary to do image comparision. I will have to use Php-OpenCV Library. If i have to allow some sort of error tolerance, the above class can work properly. My work can was achieved using Php-tesseract. I have simply used tesseract-OCR. I used ghostscript for converting the PDF into png, cropped the image, convert that particular part of image into text using Php-tesseract OCR Library that is placed on google Code website. Called that text into variable,using regexpression i was able to check that whether a particular text exists in the variable or not and used it in the condition as requried for me.
Consider this as end of my problem.
For convenience of the visitors i am pasting my Code Snippet so that it can be used.
// Cropping the image
// Get dimensions of the original image
list($current_width, $current_height) = getimagesize($file);
// The x and y co-ordinates on the original image where we will begin cropping the image
$left = 1100;
$top = 30;
// final size of image
$crop_width = 700;
$crop_height = 200;
//Resample the Image
$canvas = imagecreatetruecolor($crop_width,$crop_height);
$current_image = imagecreatefrompng($file);
imagecopy($canvas, $current_image, 0, 0, $left, $top, $current_width, $current_height);
imagepng($canvas, $file, 1);
// Note you will have to install Php tesseract Library before making the API Call.
$api= new TessBaseAPI;
$api->Init(".","eng",$mode_or_oem=OEM_DEFAULT);
$api->SetPageSegMode(PSM_AUTO);
$mImgFile = $file;
$handle=fopen($mImgFile,"rb");
$mBuffer=fread($handle,filesize($mImgFile));
//print strlen($mBuffer);
$result=ProcessPagesBuffer($mBuffer,strlen($mBuffer)*4,$api);
//print $result;
$result = ProcessPagesFileStream($mImgFile,$api);
//print "result(ProcessPagesFileStream)=";
print $result;
$txtchk = 'FORM';
if(preg_match("/$txtchk/i", $result)) {
echo true;
}
I hope it will be helpful for lot of people.