Cropping Images

godwheel

I want the script to crop from bottom and top if the image is taller than wider and if the image is wider than taller, to crop from left and right. In essence, the image should end up being 100x100. The whole script works well except for that part.

For example, when I upload an image that is 500x375, it resamples it to 133x100. This works great. However, when it actually crops it down to 100x100 it chops the image by the right-hand side, not equally from both sides. Can anyone help?

EDIT: By the way, I looked through the manual for ImageCopyResampled, but I was confused as to how the cropping aspect worked.

// Get image just moved	after upload
$originalimage_path = "$icon_folder/$icon_name_form"; // where the image to be resized is located
$destination_path = "icons/icon_".$_SESSION['login_un'].".jpg";


// Set maximum image width and height
$max_width = 100;
$max_height = 100;

// Get the submitted image information
$img = imagecreatefromjpeg($originalimage_path);
$originalwidth= imagesx($img);
$originalheight= imagesy($img);

// If the picture is taller than wider, we set the height of the thumb to 100 pixels.

if ($originalwidth < $originalheight) {
$icon_w = $max_width;
$icon_h = round(($max_height * $originalheight) / $originalwidth);
$tocrop_w = 0;
$tocrop_h = round(($icon_h-$max_height)/2);
}

if ($originalwidth > $originalheight) {
$icon_w = round(($max_width * $originalwidth) / $originalheight);
$icon_h = $max_height;
$tocrop_w = round(($icon_w-$max_width)/2);
$tocrop_h = 0;

}

if ($originalwidth == $originalheight) {
$icon_w = $max_width;
$icon_h = $max_height;
$tocrop_w = 0;
$tocrop_h = 0;

}

$actual_icon = ImageCreateTrueColor($max_width,$max_height);

ImageCopyResampled($actual_icon, $img, 0,0,$tocrop_w,$tocrop_h,$icon_w,$icon_h,$originalwidth,$originalheight);

// Now copy the image to destiny
imagejpeg($actual_icon,$destination_path,90);

konsu

did you try to extract an arbitrary part of an image and save it in another image? does this work? if so, then cropping is just a special case of this.

godwheel

I'm sorry, I don't understand the question.

But, basically, it is cropping from the right-hand side exclusively when the image is wider than it is taller. Does that make sense?

godwheel

bumparoo

konsu

once you calculated the width of the source rectangle to copy, you need to set its position so that it is in the middle of the source image. right now, i see that you call ImageCopyresampled with upper left corner of the rectangle set to (0,0).

konsu

i am wrong, you give the right source coordinates. the source width and height are wrong when you call the copy function.

konsu

in general, if you have an image of size (W,H), and you need to scale it to size (w,h), you need to find the scaling factor first, scale the image, and either crop or padd it to be of size (w,h). scaling factor depends on whether you want to crop or padd your image if it has a different aspect ratio than the desired dimensions. if you want to crop it:

S = max(h/H, w/W);

Or if you want to rather pad it:

S = min(h/H, w/W);

Once you find the S, calculate the new dimensions and either crop or pad the image by copying it in to the destination image as you do now. no need for all these if statements.