从图像中分离网格单元并裁剪它们

Question

我一直在尝试获取每周菜单 pdf 并将其分成网格框以进行裁剪，然后使用 TesseractOCR.

进行 OCR

我看过 lineJunctions which might be helpful here, but wasn't able to find them in imagemagick php documentation. I've also seen ，但还是无法在 php 文档中找到它们。

//read the image
$im = new Imagick();
$im->readimage('menu.png');

//resize and contrast
$im->resizeImage($im->getImageWidth()/6, $im->getImageHeight()/6 , 9, 1);
$im->thresholdImage( 0.65 * Imagick::getQuantum() );;

//remove "noise"
//this is done by creating two new images where only horizontal lines, then vertical are preserved using morphology and then combined into one
$horizontalLines = clone $im;
$verticalLines = clone $im;

$horizontalLineKernel = \ImagickKernel::fromBuiltIn(\Imagick::KERNEL_RECTANGLE, "19x1");
$horizontalLines->morphology(\Imagick::MORPHOLOGY_CLOSE, 1, $horizontalLineKernel);

$verticalLineKernel = \ImagickKernel::fromBuiltIn(\Imagick::KERNEL_RECTANGLE, "1x15");
$verticalLines->morphology(\Imagick::MORPHOLOGY_CLOSE, 1, $verticalLineKernel);

$horizontalLines->compositeimage($verticalLines, 5, 0, 0);

$im = clone $horizontal;

$horizontalLines->clear(); 
$horizontalLines->destroy();
$verticalLines->clear(); 
$verticalLines->destroy();

// Create boxes at corners
// These are at points from which I intent to create the individual grid boxes
$plusKernel = \ImagickKernel::fromBuiltIn(\Imagick::KERNEL_PLUS, "4");
$im->morphology(\Imagick::MORPHOLOGY_OPEN, 1, $plusKernel);

$squareKernel = \ImagickKernel::fromBuiltIn(\Imagick::KERNEL_SQUARE, "2");
$im->morphology(\Imagick::MORPHOLOGY_CLOSE, 1, $squareKernel);

通过这样做，我最终得到了一个带有框的图像，如果我可以获得 x、y、宽度和高度，我应该能够获得坐标，但是它错过了右下角并且非常混乱。我相信一定有更好的方法。

图像已缩小，然后我计划将坐标放大 6，如 $im->resizeImage() 所示。有没有更好的方法来解决这个问题？

Answer 1

在 ImageMagick 中执行此操作的一种方法（假设线条是水平和垂直的）是缩放到一行和一列、阈值和过滤器 txt：黑色像素的输出。

xlist=`convert cells.png -scale x1! -auto-level -threshold 27% -negate -morphology Thinning:-1 Skeleton -negate txt:- | grep "black" | cut -d, -f1`
echo "$xlist"
38
109
180
251
322
394
465
536


ylist=`convert cells.png -scale 1x! -auto-level -threshold 27% -negate -morphology Thinning:-1 Skeleton -negate txt:- | grep "black" | cut -d: -f1 | cut -d, -f2`
echo "$ylist"
45
141
256
381

所有 x 值和所有 y 值的组合为您提供交集数组。

xArr=($xlist)
yArr=($ylist)
numx=${#xArr[*]}
numy=${#yArr[*]}
pointlist=""
for ((j=0; j<numy; j++)); do
for ((i=0; i<numx; i++)); do
pointlist="$pointlist ${xArr[$i]},${yArr[$j]}"
done
done
echo "pointlist=$pointlist"
pointlist= 38,45 109,45 180,45 251,45 322,45 394,45 465,45 536,45 38,141 109,141 180,141 251,141 322,141 394,141 465,141 536,141 38,256 109,256 180,256 251,256 322,256 394,256 465,256 536,256 38,381 109,381 180,381 251,381 322,381 394,381 465,381 536,381

您可以通过以下方式可视化：

convert cells.png -scale x1! -scale 550x50! -auto-level -threshold 27% tmp1.png

convert cells.png -scale 1x! -scale 50x425! -auto-level -threshold 27% tmp2.png

没有细化，顶部水平线比一个像素粗。

从图像中分离网格单元并裁剪它们

Separating grid cells from an image and cropping them

php

image

imagemagick

image-morphology