How do i resize image preserving its dimension ratio proportion and transparancy in php
Use the GD library from MicroMVC. It's the smallest, fastest GD lib out there.
The function you want is called imagecopyresampled(); don't forget to only use true color images for destinations. Here is a comment which talks specifically about preserving transparency: http://www.php.net/manual/en/function.imagecopyresampled.php#93166 (note the usage of the imagecolorallocatealpha() function)
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I have pieced together a PHP class to perform various image related functions using GD functions of PHP.
It works great for all image types. Rotate, flip, resize, crop and to a lesser extent, watermark.
All but the latter work perfectly. For example after a few changes, rotated PNG images retained their transparency whereas before they were losing that and the background turning black. Common problem, it appears. But all working now.
Where I'm still getting stuck is watermarking a PNG image with another PNG image. It appears to work fine with JPG and other images. This is the code (simplified):
public function writeWatermarkSimple()
{
$watermarkFile = 'watermark.png';
$watermarkImage = imagecreatefrompng($watermarkFile);
imagealphablending($watermarkImage, false);
imagesavealpha($watermarkImage, true);
$imageFile = 'image.png';
$baseImage = imagecreatefrompng($imageFile);
imagealphablending($baseImage, false);
imagesavealpha($baseImage, true);
$marginH = imagesx($baseImage) - imagesx($watermarkImage);
$marginV = imagesy($baseImage) - imagesy($watermarkImage);
$cut = imagecreatetruecolor(imagesx($watermarkImage), imagesy($watermarkImage));
imagecopy($cut, $baseImage, 0, 0, $marginH, $marginV, imagesx($watermarkImage), imagesy($watermarkImage));
imagecopy($cut, $watermarkImage, 0, 0, 0, 0, imagesx($watermarkImage), imagesy($watermarkImage));
imagecopymerge($baseImage, $cut, $marginH, $marginV, 0, 0, imagesx($watermarkImage), imagesy($watermarkImage), 80);
if (!imagepng($baseImage, 'watermarked_image.png'))
{
return false;
}
return true;
}
This has been pieced together with various guides and advice people have given based on a similar issue. Again, working perfectly with JPG images and PNG watermarks, but not PNG & PNG.
Some example images:
http://i.imgur.com/hHRWinj.png - This is the watermark I'm using.
http://i.imgur.com/6sy8Ncs.png - This is the image I'm applying the watermark to.
http://i.imgur.com/ghovYLm.png - This is the end result.
The bit I find interesting is that any part of the watermark that is overlaid on a non-transparent portion of the image is working fine. Just the rest of it has the black background.
This leads me to believe I'm close, and I hope that the expertise of you fine people may lead me to the solution.
Thanks ever so for reading.
So, I'm not giving up on finding the correct answer to do this using GD. However, I was overjoyed to find that what needed up to 30 lines of code with GD can be achieved using much less with ImageMagick:
$image = new Imagick();
$image->readimage($this->_image);
$watermark = new Imagick();
$watermark->readimage($this->_watermark->_getImage());
$watermark->evaluateImage(Imagick::EVALUATE_DIVIDE, 2, Imagick::CHANNEL_ALPHA);
$image->compositeImage($watermark, imagick::COMPOSITE_OVER, $marginH, $marginV);
So this is before (with GD):
http://i.imgur.com/AlS0TcO.png
And after (with ImageMagick and the code above):
http://i.imgur.com/zBxlC3R.png
If anyone has an answer that is purely GD then I'd be immensely grateful.
Ran into some similar issues recently and while this may not exactly solve your problem, these were some useful discoveries that I made.
In my case, I have an original .jpg image and a watermark .png image. The watermark image has a fully transparent background. I wanted to specify the opacity in my script and have it change the watermark opacity before placing it on top of the origina image. Most posts out there regarding PHP watermarking assume that the original watermark .png file already has the solid watermark portion set to the correct opacity rather than changing it via the script.
gd didn't like a 24 bit .png and caused some goofy issues. Switching to 8 bit resolved that with gd. On the other hand, imagick works very well with a 24 bit .png and the final result seems to be better.
For me, using gd worked just fine if I was opening the original watermark .png and using imagecopymerge() to set the watermark transparency. If however I tried to scale the original watermark .png (which has transparent background) first, then I would get similar results as you with black or white background portion of where watermark image is. See How do I resize pngs with transparency in PHP? for a partial solution by filling the new wm image with transparent rectangle first. For me this still produced an opaque white background on the final result no matter what I tried.
I switched to imagick and was using setImageOpacity() to change the transparency of my watermark .png before applying it on top of my original image and I was still getting the same effect with a black background. Finally read in the PHP doc for setImageOpacity() that if the original .png has any transparent pixels and you try to lower the opacity, those pixels become opaque (black) with the new transparency applied. Instead, need to use the evaluateImage() function. This will instead evaluate each pixel's alpha channel only and divide by the specifid number.
I assume the black / white background issue with gd is likely due to similar ways that it treats alpha channels when scaling / combining as compared to imagick and if you want to do it all in gd you just need to find some similar way to evaluate and manipulate the alpha channel per-pixel because the "easy" ways seem to take an already transparent background and make it opaque.
So, the solution:
Assuming you want to apply your watermark at an opacity of 45% and you're using imagick, then instead of this:
$watermark->setImageOpacity(.45);
do this
$watermark->evaluateImage(Imagick::EVALUATE_DIVIDE, (1/.45), Imagick::CHANNEL_ALPHA);
You need to divide 1 by your opacity to get the demoninator by which the function will divide the alpha channel value for each pixel. In this case, 1/.45 = 2.2222, so then the function will divide the alpha channel of each pixel by 2.2222. This means a solid pixel (alpha of 1) would result in 1/2.2222 or .45 alpha or transparency when finished. Any pixels that were already transparent (alpha 0) would stay transparent because 0 divided by anything is always what? Zero!
After you change the watermark transparency then you can use compositeImage() to merge the watermark onto the original image.
I did found a topic similar to this, but I do not know if the solution is the same. So here is my question:
I'm using the GD functions to bild a web card generating program. The thing is that the card's backgound is generating by the $image = imagecreatefrompng(); function.
The card need's also a $cardname as "title" and a $desription as desription. For that I used the imagettftext(); function. But there is a problem, the card's size is 333x485, I need the text to be resized in order to fit in the background without resizing its height, but only the width!
To be more to the point, the $cardname should have width = 240 and height = 34, but if it doesn't fit, it goes off the background, I need a function that will resize its width in order to fit in 240px and leave the height to 34px always!
To understand it more look here: http://yugiohcardmaker.net. in the "name" you can add as much text you like, it will always fit in and in the right width and height!
I'm not going to try and code this as it will take too long, but here's the basic process:
Get the size of the bounding box for your text with imagettfbbox();
Create a new image with imagecreatetruecolor();
Write your text into your new image with imagettftext();
Use imagecopyresampled() to copy the new image with your text to your existing card, setting the parameters to shrink the width but not the height.
Note: the bounding box parameters returned by imagettfbbox()) can be fiddly to work with
You'll also need to be careful about alphablending and background colors to ensure that only your text pixels are copied.
Good luck!
I have an image that is 180x240 and I want to pad/border it with white until it fits the size 360x240, so the original content from image won't get distort.
http://www.magickwand.org/ - I can't find any suggestive function in the documentation
I do not use Magickwand but with Imagemagick there is an operator called extent which does what you want. But I can not see any mention of extent in the documentation you linked.
You may have to create a white canvas of 360x240 and composite your image onto it.
Alternativly could you use MagickBorderImage and have the border set to 0 or 1 on the height and 90 on the width?
I'm making a skin previewer for my site; I need to rotate parts of an image to create a representation of this for my users to see.
The skin is a PNG file, and all parts of it may have transparency or even none at all.
I need to be able to rotate this image while keeping any transparency inside the image transparent, while also having the extended borders (You know, the area that wasn't part of the image before it was rotated) transparent.
All of my attempts have left a black border around the image itself.
Any help?
Cut out the piece of the image you want to rotate
Rotate preserving alpha using something like this http://www.exorithm.com/algorithm/view/rotate_image_alpha
Merge back in preserving alpha using the following:
-
imagesetbrush($destimg, $srcimg);
// x, y are the center of target paste location
imageline($destimg, $x, $y, $x, $y, IMG_COLOR_BRUSHED);
I use that to rotate a PNG and preserve transparency color. Works like a charm. It's "basic GD".
$rotation = 135;
$handle_rotated = imagerotate($handle_not_rotated,$rotation,0);
imagealphablending($handle_rotated, true);
imagesavealpha($handle_rotated, true);
Don't know if it's what you're looking for?
You may want to check here for some uses for libpng (which will need zlib). If you are on linux you can write something in perl. CPAN GD module might be your ticket.
I'm writing code this week to dynamically change the color of images. As long as the image is square or rectangle, the code below works perfectly. However, I have an image that has rounded corners (filled with a spot color and the background outside the corners is white.)
Can someone tell me if there's a simple way to color an image that has rounded corners using the imagecolorset function (or any other php method)?
I only want the non white areas of the image to be colored (In case you're wondering, I'm disallowing the color white to be applied to the image).
Note, perhaps a better way to do this would be to use a PNG image that has transparent background (rather than my gif image). If you think that's a better approach, please advise.
Here's the function that I'm working with...
function set_theme_color_header($hex)
{
$info = hexToRGB($hex); //calls a helper function which translates the hex to RGB
$img = imagecreatefromgif('header-template.gif'); //again, this could be a PNG image, but we always start with this image, then create a color copy
$color = imagecolorallocate($img, $info["red"], $info["green"], $info["blue"]);
imagecolorset($img, 0, $info["red"], $info["green"], $info["blue"]);
imagegif($img, 'header.gif'); //only problem is that the imagecolorset function creates a messy fill at the corners
}
GD does not handle gif's very well. I recommend creating a png image with your rounded corners, then use GD's imagefilter($img, IMG_FILTER_COLORIZE, $info["red"], $info["green"], $info["blue"], $alpha) function. Then save the image as a gif.
Alternatively, use php's imagick library to literally draw the image. imagick is about a billion times better than GD. Poorly documented, but...the basic stuff isnnt too hard. See the tut link below.
Search php.net for "imagick" to see all the functions.
imagick tutorial
i really do not not why you are doing this, but maybe have a look at phpTumb (and its demos here).