Hey having some trouble trying to maintain transparency on a png when i create a thumbnail from it, anyone any experience with this? any help would be great, here's what i am currently doing:
$fileName= "../js/ajaxupload/tees/".$fileName;
list($width, $height) = getimagesize($fileName);
$newwidth = 257;
$newheight = 197;
$thumb = imagecreatetruecolor($newwidth, $newheight);
imagealphablending($thumb, true);
$source = imagecreatefrompng($fileName);
imagealphablending($source, true);
imagecopyresized($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
imagesavealpha($thumb, true);
imagepng($thumb,$newFilename);
I have had success doing it like this in the past:
$thumb = imagecreatetruecolor($newwidth, $newheight);
imagealphablending($thumb, false);
imagesavealpha($thumb, true);
$source = imagecreatefrompng($fileName);
imagealphablending($source, true);
imagecopyresampled($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
imagepng($thumb,$newFilename);
I found the output image quality much better using imagecopyresampled() than imagecopyresized()
Forget the color transparency index, it never works in all rendering products. Instead use an alpha layer mask:
$image = imagecreatetruecolor($size, $size);
imagealphablending($image, false);
imagesavealpha($image, true);
$trans_layer_overlay = imagecolorallocatealpha($image, 220, 220, 220, 127);
imagefill($image, 0, 0, $trans_layer_overlay);
Those functions access the underlying gdlib library, which is a fine toy, but not something that makes for nice results. If you have the option, use imagemagick instead. The downside is that there are currently no good php-bindings, so you need to access it over the shell, which you're usually not allowed on shared hosts.
See dycey's answer to "How do I resize...". Essentially, you need to fill the entire background with transparency before you do any other operations.
imagecopyresized does not support transparency properly.
imagecopymerge does, but it doesn't resize.
The solution? You'd probably end up resizing the thing manually.
Related
I'm refactoring an old image crop/resize library i wrote about 5 years ago and i'm stuck trying to restore one of it's functionalities. The funny part is that i'm not even sure it worked back then since i probably never actually used it.
I need to be able to work on png images while keeping transparency (which works), but i also wan't to be able to fill the transparent part of the image with a color.
Creating a blank image and filling it with a color works fine, but when i try to paste my png over it, the background is transparent again.
Here's a simplified version of my code:
<?php
$src = imagecreatefrompng($pathToSomePngFile);
imagealphablending($src, false);
imagesavealpha($src, true);
$output = imagecreatetruecolor($width, $height);
if ($backgroundColor) {
$fillColor = imagecolorallocate(
$output,
$backgroundColor['r'],
$backgroundColor['g'],
$backgroundColor['b']
);
imagefilledrectangle(
$output,
0,
0,
$width,
$height,
$fillColor
);
} else {
imagealphablending($output, false);
imagesavealpha($output, true);
}
imagecopyresampled(
$output,
$src,
0,
0,
0,
0,
$width,
$height,
$width,
$height
);
imagepng($output, $pathToWhereImageIsSaved);
UPDATE
Updated with delboy1978uk's solution to get it to work without changing my other settings.
Something like this should work.
<?php
// open original image
$img = imagecreatefrompng($originalTransparentImage);
$width = imagesx($img);
$height = imagesy($img);
// make a plain background with the dimensions
$background = imagecreatetruecolor($width, $height);
$color = imagecolorallocate($background, 127, 127, 127); // grey background
imagefill($background, 0, 0, $color);
// place image on top of background
imagecopy($background, $img, 0, 0, 0, 0, $width, $height);
//save as png
imagepng($background, '/path/to/new.png', 0);
I've a png image uploading script in my website and i'm scaling down the large images to small size and i'm using this code but it loses the transparent background
$image = $tmp; // Uploaded Image
$maxImgWidth = 224;
$src = imagecreatefrompng($image);
list($width, $height) = getimagesize($image);
$newwidth = $maxImgWidth;
$newheight = ($height / $width) * $newwidth;
$newImage = imagecreatetruecolor($newwidth, $newheight);
imagealphablending($image, true);
imagesavealpha($image, true);
imagecopyresampled($newImage, $src, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
imagepng($newImage, "../thumb/$name_after-$code.$ext", 1);
imagedestroy($src);
imagedestroy($newImage);
This code makes the image without transparency :
And i want with transparent background like this one :
Sorry I have no experience in PHP but after I read this page, I think you may need add the transparent colour after you set the save alpha is true
imagesavealpha($image, true);
$color = imagecolorallocatealpha($image, 0, 0, 0, 127);
imagefill($image, 0, 0, $color);
if still cannot try add this after imagecolorallocatealpha(),
imagecolortransparent($image, $color);
I have a script that resizes uploaded images. It works fine for PNGs and JPGs but with GIFs it renders the transparency in the resized GIF black.
$src = imagecreatefromgif($file);
$dst = imagecreatetruecolor($newWidth, $newHeight);
imagecopyresampled($dst, $src, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);
imagegif($dst, $file);
From the manual page http://us3.php.net/manual/en/function.imagecopyresampled.php#104028
imagecolortransparent($new, imagecolorallocatealpha($new, 0, 0, 0, 127));
imagealphablending($new, false);
imagesavealpha($new, true);
is used by one poster to preserve transparency.
Here's a tip... Always check out user comments on php.net as they are generally very helpful in understanding the nuances of a function and providing tips for handling common tasks.
I'm assuming this goes to a web-page, which if it does you could just output the image tag with the correct attributes?
echo "<img src='$file' width='$newWidth' height='$newHeight' />";
You still have to set the transparency in the new image. The following is taken from the php docs:
<?php
// Create a 55x30 image
$im = imagecreatetruecolor(55, 30);
$red = imagecolorallocate($im, 255, 0, 0);
$black = imagecolorallocate($im, 0, 0, 0);
// Make the background transparent
imagecolortransparent($im, $black);
// ^^ This is the command you are missing.
// Draw a red rectangle
imagefilledrectangle($im, 4, 4, 50, 25, $red);
// Save the image
imagepng($im, './imagecolortransparent.png');
imagedestroy($im);
?>
In your case, you want to make the transparency the same color as the original transaprency - which I always made a hideous purple or something that would a) stick out like a sore thumb in my image manipulation software and secondly, have a RGB key that was almost impossible to have included in an image by mistake.
When using examples from other posts to try and merge one PNG that has transparent parts on it with another non-transparent PNG, the foreground PNGs transparency is lost and defaults to white.
The code so far:
$width = 349;
$height = 250;
$base_image = imagecreatefrompng($_GET['bg']);
$top_image = imagecreatefrompng($_GET['fg']);
$merged_image = "merged.png";
imagesavealpha($top_image, true);
imagealphablending($top_image, true);
imagecopy($base_image, $top_image, 0, 0, 0, 0, $width, $height);
imagepng($base_image, $merged_image);
Can anyone suggest where I may be going wrong?
Coming out like this
Should look like this
Copy from Can PNG image transparency be preserved when using PHP's GDlib imagecopyresampled?
Codes should be like this:
imagesavealpha($base_image, true);
imagealphablending($base_image, false);
$image = imagecreatefrompng($_GET['bg']);
$frame = imagecreatefrompng($_GET['fg']);
imagealphablending($frame,true);
imagecopymerge($image, $frame, 0, 0, 0, 0, 0, 100, 100);
# Save the image to a file
imagepng($image, 'file-xyz.png');
I have a small class which handles image manipulation.
I use following to resize a image
$this->image = imagecreatefrompng($filename);
....
$new_image = imagecreatetruecolor($width, $height);
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
...
$this->image = $new_image;
imagepng($this->image,$filename)) { return true; }
But the resized image is not preserving transparency, instead black is comming, how can i preserve the transparency.
Update
After, using #Manuel's code, black portion has decreased, but still black background are still present. The source image and the resulting image are
Source & Sub corresponding
main http://www.freeimagehosting.net/newuploads/820a0.png sub http://www.freeimagehosting.net/newuploads/30526.png
The newest comment, posted on the 8th of May, on the manual page for imagecopyresampled, tells you how to do this.
imagecolortransparent($new_image, imagecolorallocatealpha($new_image, 0, 0, 0, 127));
imagealphablending($new_image, false);
imagesavealpha($new_image, true);
Put that right after creating $new_image.
add this before the imagecopyresampled(...)
// preserve transparency
imagecolortransparent($new_image , imagecolorallocatealpha($new_image , 0, 0, 0, 127));
imagealphablending($new_image , false);
imagesavealpha($new_image , true);