I use the following combination of functions
$img_r = imagecreatefrompng($src);
$dst_1 = imagecreate( $targ_w_1, $targ_h_1 );
imagecopyresampled($dst_1,$img_r,0,0,0,0,$targ_w_1,$targ_h_1,$size_test[0],$size_test[1]);
imagepng($dst_1, $final_source_1,9);
Final result comes with very low quality, as I understand imagepng max quality is 9. You cannot write 100 there. But still quality is very bad. maybe I use wrong functions to manipulate with image ? Any suggestions ?
original 220x220 image
resized image to size 120x120
resized image with the same size 220x220
SOLVED
Look in the manual. It has this to say on imagepng()'s $quality parameter:
Compression level: from 0 (no compression) to 9.
So 9 seems to be the worst quality level. Try a lower setting.
As far as I know, there is no such thing as a quality setting in the PNG-format, nor in the underlying c-library. There is compression, but since PNG is a loss-less format, compressing the image does not degenerate the quality.
The compression setting of 9 gives the best compression (=smallest file size).
The issue you run into likely is that your destination image is created with imagecreate(); a paletted image.
You are more likely looking for imagecreatetruecolor()
Problem was with alpha . After I read Jaccos comment I went to google and found this
imagealphablending($dst_1, false);
imagesavealpha($dst_1,true);
$transparent = imagecolorallocatealpha($dst_1, 255, 255, 255, 127);
imagefilledrectangle($dst_1, 0, 0,$targ_w_1, $targ_h_1, $transparent);
This peace of code must be put right after imagecreatetruecolor ad everything will be just fine :)
Related
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
$watermark->evaluateImage(Imagick::EVALUATE_DIVIDE, (1/.45), Imagick::CHANNEL_ALPHA);
You need to divide 1 by your opacity to get the demoninator by which the function will divide the alpha channel value for each pixel. In this case, 1/.45 = 2.2222, so then the function will divide the alpha channel of each pixel by 2.2222. This means a solid pixel (alpha of 1) would result in 1/2.2222 or .45 alpha or transparency when finished. Any pixels that were already transparent (alpha 0) would stay transparent because 0 divided by anything is always what? Zero!
After you change the watermark transparency then you can use compositeImage() to merge the watermark onto the original image.
While i was doing some image processing, i found out that GD and Imagick in PHP does not resize image to color pixel identical level, which in most cases, were not needed.
Now in case, i need a image from whatever dimension to scale to 256*256
To make sure the TEST results are consistent, i used a 256*256 image and resize it to it's own size.
what i've attempted:
imagecopyresized($new, $img, 0, 0, $x, 0, $width, $height, $w, $h); //256 , 256
and
$compression_type = imagick::COMPRESSION_NO;
$images_ima = new Imagick($image_path); //$image_path = path to image...
$images_ima->setImageCompression($compression_type);
$images_ima->setImageCompressionQuality(100);
$images_ima->sampleImage($X_SIZE,$Y_SIZE); // 256 ,256
$images_ima->writeImages($dest_path, true); //destination path
none of them worked, if i compare the output with the original image, it will look something like this:
it looks like the functions i've used are resampling the image since the variations in the RGB value between both image are small
i can achieve pixel to pixel identical resizing from 256*256 to 256*256 in photoshop, OSX preview, and even Pixelformer.
i was wondering how can that be done i PHP?
Since your image format (jpeg - assumed from 100 quality setting) is a lossy format you won't get a lossless throughput this way as you're recompressing the image.
You should try to detect image dimensions and use the original image if the dimensions are already correct.
When you don't change the dimensions (original dimensions = dimensions after resizing) in Photoshop or OSX preview they won't recompress the image, that's why you won't see any change.
Not sure why it looks so bad, but when I copy an image over another image, it looks extremely terrible, like it lost almost all its colors for some reason.
$img = imagecreate(240, 140);
$wall = imagecreatefrompng($src);
imagecopyresampled($img, $wall, 0, 0, 40, 340, 240, 140, 240, 140);
I've been trying to find a solution myself but I can't seem to find one, anybody really good with GD that can help? I can't use imagemagick.
You need to create your canvas image with imagecreatetruecolor() rather than imagecreate() as the former creates a palette based canvas with limited colour support.
I presume you are then using imagepng() to save our output the image. The third argument accepted by this function defines the quality of the image, or the compression level (0-9)
I am resizing images using:
//load file and dimensions
$obj_original_image = imagecreatefromjpeg($str_file_path);
list($int_width, $int_height, $image_type) = getimagesize($str_file_path);
//compress file
$int_thumbnail_width = 320;
$int_ratio = $int_thumbnail_width / $int_width;
$int_new_width = $int_thumbnail_width;
$int_new_height = $int_height * $int_ratio;
$obj_image = imagecreatetruecolor($int_new_width, $int_new_height);
imagecopyresampled($obj_image, $obj_original_image, 0, 0, 0, 0, $int_new_width, $int_new_height, $int_width, $int_height);
imagejpeg($obj_image, $GLOBALS['serverpath'] . '/images/uploaded/video-thumbs/'.$arr_data['thumbnail_folder'].'/' . $arr_data['id']. '.jpg', $int_compression = 85);
And this is generally working perfectly. However occasionally, it is producing a blank, white image. I have read this note at http://php.net/manual/en/function.imagecopyresampled.php:
There is a problem due to palette image limitations (255+1 colors). Resampling or filtering an image commonly needs more colors than 255, a kind of approximation is used to calculate the new resampled pixel and its color. With a palette image we try to allocate a new color, if that failed, we choose the closest (in theory) computed color. This is not always the closest visual color. That may produce a weird result, like blank (or visually blank) images. To skip this problem, please use a truecolor image as a destination image, such as one created by imagecreatetruecolor().
However, I am already using imagecreatetruecolor. I am always scaling the same sized images so it can't be a width/height issue. It is only happening sometimes, most times the image scaling is working fine. Any ideas as to how to fix this?
There's no reason to be using getimagesize() when you've already opened the image with imagecreatefromjpeg(). You can use the imagesx() and imagesy() to get the width/height. getimagesize is seperate from GD and will re-open the image, re-parse it, etc...
Also note that GD is pretty stupid and forces you to determine what image type you've got and call the appropriate createfrom function. imagecreatefromjpeg() will fail if you try to open anything OTHER than a .jpg image.
$obj_original_image = imagecreatefromjpeg($str_file_path);
if ($obj_original_image === FALSE) {
die("Unable to load $str_file_path. Not a jpg?");
}
etc... etc...
$status = imagecopyresampled($obj_image, $obj_original_image, 0, 0, 0, 0, $int_new_width, $int_new_height, $int_width, $int_height);
if ($status === FALSE) {
die("imagecopyresampled failed!");
}
As well, add some debugging to your height/width calculations - output the values you're generating. Maybe one or more of them is coming out as 0, so you end up resampling to a non-existent size.
You mentioned that the size of the image being processed is always the same, but is the resolution always the same? If you have a particularly high resolution image you're working with, you may be running out of memory for certain operations which will produce a blank white image, in my experience. If this is the case, you could try to fix it by increasing the amount of memory allocated to PHP in php.ini under the memory_limit parameter. As far as I know, that value applies to image manipulations.
I have a watermark script I am working on, the results are good on PNG and on JPG images however a gif image, not so good. I am using PHP and GD
Below you can see the difference in quality of the watermark.
Anyone know how to improve this?
For the gif version I am using
$image = imagecreatefromgif($source_file);
imagecopymerge($image, $watermark, $x, $y, 0, 0, $water_width, $water_height, 65);
imagegif($image, $source_file);
gif image = bad quality
gif image http://img2.pict.com/fd/46/00/1471179/0/gif.gif
jpg image = good
jpg image http://img2.pict.com/82/a1/5a/1471181/0/jpg.jpg
GIF images have a fixed palette that can contain a maximum of 256 colors. The issue here is probably that the image your inserting uses colors that isn't available in the target image.
I have never tried this, but it might be worth a shot. You could try converting the gif image to a true color image first, then do the watermarking and after that converting it back to gif.
$image = imagecreatefromgif($source_file);
// create a true color image of the same size
$image2 = imagecreatetruecolor(imagesx($image), imagesy($image));
// copy the original gif image on to the true color image
imagecopy($image2, $image, 0, 0, 0, 0, imagesx($image), imagesy($image));
// copy the watermark onto the new true color image
imagecopymerge($image2, $watermark, $x, $y, 0, 0, $water_width, $water_height, 65);
// write the new image to disk
imagegif($image2, $source_file);
Try it and see if it makes a difference.
There's also a couple of palette manipulation functions available that might help:
imagecolormatch()
imagetruecolortopalette()
imagepalettecopy()
I'm not sure how you would apply them, but I'm guessing that there's a few things you could do to improve the results.
GIF only supports a color palette of 256 colors. Therefore, the colors of your watermark image have to be mapped to this palette. This caused them to be rendered and saved with different colors than before. Due to this small palette, GIF is not recommended for photos in general, anyways.
GIF images will never look great, as the colour palette is 256 colours. As MrMage says, colour mapping causes a severe approximation of the true colours of the image. You are better off with PNGs, they do support transparency.