how is it possible to save my image, created with gd, as an png-8?
it saves as gif with transparent channel well - but I want to use png-8.
Best Regards,
Beerweasle
Using imagesavealpha() and a transparent bg color should do the trick...
Based on dfilkovi's code:
<?php
// Create a new true color image
$im = new imagecreatetruecolor(100, 100);
// Fill with alpha background
$alphabg = imagecolorallocatealpha($im, 0, 0, 0, 127);
imagefill($im, 0, 0, $alphabg);
// Convert to palette-based with no dithering and 255 colors with alpha
imagetruecolortopalette($im, false, 255);
imagesavealpha($im, true);
// Save the image
imagepng($im, './paletteimage.png');
imagedestroy($im);
?>
#Sonny
false assumption: PNG of any bit depth can have transparency. It is recorded in the tRNS chunk of the png image (except for truecolor ones) cf format definition
cf www.libpng.org/pub/png/spec/1.2/PNG-Chunks.html#C.tRNS
idem www.w3.org/TR/PNG-Chunks.html#C.tRNS
The difference is how it is recorder: RGBA has a unique record per pixel, with 4 values (3 colors and 1 alpha channel), where "paletted" PNG records alpha channel in its own chunk.
Fireworks is very good at it.
Examples:
http://www.libpng.org/pub/png/pngs-img.html
I think this could help you.
http://roseindia.net/tutorial/php/phpgd/About-transparent.html
<?php
// Create a new true color image
$im = new imagecreatetruecolor(100, 100);
// Convert to palette-based with no dithering and 255 colors
imagetruecolortopalette($im, false, 255);
// Save the image
imagepng($im, './paletteimage.png');
imagedestroy($im);
?>
this should make 8bit png
Building on dfilkovi's solution, have you tried using imagesavealpha() to save the full alpha channel information?
I had to add the line imagecolortransparent($im, $alphabg); to the following code (taken from previous answer) for this to work:
// Fill with alpha background
$alphabg = imagecolorallocatealpha($im, 0, 0, 0, 127);
imagecolortransparent($im, $alphabg);
imagefill($im, 0, 0, $alphabg);
// Convert to palette-based with no dithering and 255 colors with alpha
imagetruecolortopalette($im, false, 255);
imagesavealpha($im, true);
// Save the image
imagepng($im, './paletteimage.png');
imagedestroy($im);
?>
Related
In css, we have a property called "z-index", what is the same in PHP GD and Image Functions to control the "z-index"?
I've been searching but I can't find one, please help.
Thankyou
there nothing existing like z-index in php GD library
but there several ways to overlap image over image or text over image
$redimg = imagecreatetruecolor(100, 100);
$image = imagecreatefrompng('image.png');
// sets background to red
$red = imagecolorallocate($redimg, 255, 0, 0);
imagefill($redimg, 0, 0, $red);
// Merge the red image onto the PNG image
imagecopymerge($image, $redimg, 0, 0, 0, 0, 100, 100, 75);
header('Content-type: image/png');
imagepng($image);
imagedestroy($image);
imagedestroy($redimg);
here one example, or let me know, what exactly you trying to do, I will help you
There's more information here.
I need some help about PHP GD. Here is my piece of code.
header("Content-type: image/gif");
$image = imagecreatetruecolor(550, 20);
imagealphablending($image, false);
$col=imagecolorallocatealpha($image,255,255,255,127);
$black = imagecolorallocate($image, 0, 0, 0);
imagefilledrectangle($image,0,0,550,20,$col);
imagealphablending($image, true);
$font_path = 'font/arial.ttf';
imagettftext($image, 9, 0, 16, 13, $black, $font_path, $lastlisten);
imagesavealpha($image, true);
imagepng($image);
The problem is when I use imagepng, it can show the png just fine like this.
But if I use imagegif instead, it will become this.
I did tried using different header for gif and png. The result for imagegif is still the same.
The question is how do I make in order to display GIF version properly? Thanks you
GIF image supports a maximum of 256 colors. Most importantly, it only supports index transparency: a pixel can be 100% opaque or 100% transparent.
PNG on the other hand supports true (millions of) color images and supports alpha channel transparency. That means a pixel can be 100% opaque, 100% transparent or anything in between.
The PNG image you mentioned probably has its edges partially transparent therefore the browser can easily blend those pixels with the background color giving a smooth effect. PNG is a better choice.
First problem : your characters are ugly: that's because you need to set a palette with less colors when using imagecreatetruecolor.
$image = imagecreatetruecolor(550, 20);
imagetruecolortopalette($image, true, 256);
should solve this problem.
Second problem : there is no transparency.
As you can see on PHP manual,
imagesavealpha() sets the flag to attempt to save full alpha channel
information (as opposed to single-color transparency) when saving PNG
images.
This function does not work with GIF files.
You can use imagecolortransparent instead but this will not be perfect because fonts has anti-aliasing to make their border sweeter.
Here is my code:
<?php
$lastlisten = "test test test test test test";
error_reporting(E_ALL);
header("Content-type: image/gif");
$image = imagecreatetruecolor(550, 20);
imagetruecolortopalette($image, true, 256);
$transparent=imagecolorallocatealpha($image,255,255,255,127);
imagecolortransparent( $image, $transparent);
imagefilledrectangle($image,0,0,550,20,$transparent);
$black = imagecolorallocate($image, 0, 0, 0);
$font_path = dirname(__FILE__) . '/font.ttf';
imagettftext($image, 9, 0, 16, 13, $black, $font_path, $lastlisten);
imagegif($image);
Result here
Hope this helps.
I would like to change the color of an image with php.
if I wanted to make it appear redder applicherei an image on a higher level across an image with a transparent red and more or less high can indicate how the original photo should be red.
I can say gd php functions to create an image of a color (RGBA) and apply it to another image?
thanks :)
You can try using GD's imagecopymerge function, which copies one image to another and supports alpha transparency. Something like this should work:
<?php
$redimg = imagecreatetruecolor(100, 100);
$image = imagecreatefrompng('image.png');
// sets background to red
$red = imagecolorallocate($redimg, 255, 0, 0);
imagefill($redimg, 0, 0, $red);
// Merge the red image onto the PNG image
imagecopymerge($image, $redimg, 0, 0, 0, 0, 100, 100, 75);
header('Content-type: image/png');
imagepng($image);
imagedestroy($image);
imagedestroy($redimg);
?>
There's more information here.
I need to create a PNG image from 4 parts of another PNG image with different levels of transparency using GD library in PHP. For example:
Result should look like this
I tried to do this thing in different ways but I coudn't achieve the desired result.
Thank you in advance ;)
Load your image with imagecreatefrompng(). Create a truecolor image with imagecreatetruecolor() and then set it fully transparent with imagecolorallocatealpha() and imagefill(). Then set alpha blending mode for both the source and destination images with imagealphablending(). After this you can use imagecopymerge() to copy the image with alpha.
Unfortunately it's not possible to enforce an alpha multiplier for imagecopymerge(), so this will get you only halfway there -- Inconvenient options include repeating imagecopymerge() calls on those parts of the image you want to be less transparent, choosing between several source images depending on the level of transparency you want to use, or going through the image pixel-by-pixel, which is inconveniently slow.
If you are not married to the image* functions, consider using ImageMagick instead. It is much more robust.
I did this:
$output = imagecreatetruecolor([width], [height]);
imagesavealpha($output , true);
$trans_colour = imagecolorallocatealpha($output , 0, 0, 0, 127);
imagefill($output , 0, 0, $trans_colour);
Now the image is transparent :)
The whole script:
$output = imagecreatetruecolor([width], [height]);
imagesavealpha($output , true);
$trans_colour = imagecolorallocatealpha($output , 0, 0, 0, 127);
imagefill($output , 0, 0, $trans_colour);
header('Content-Type: image/png');
imagepng($output);
imagedestroy($output);
Hope it helps!
This worked for me with both gif and png (of course, change every reference of png in this example to gif if using that image type).
$virtual_image = imagecreatetruecolor($desired_width, $desired_height);
$colour = imagecolorallocate($virtual_image,255,255,255);
imagefill($virtual_image , 0, 0, $colour);
imagealphablending($virtual_image,true);
imagesavealpha($virtual_image , true);
//the next line only if you're resizing to a new $width/$height, otherwise leave this line out
imagecopyresampled($virtual_image, $source_image, 0, 0, 0, 0, $desired_width, $desired_height, $width, $height);
header('Content-Type: image/png');
if (imagepng($virtual_image)) imagedestroy($virtual_image);
i'm working on creating one PNG image from two others.
Image A and B have the same dimensions, they are both 200x400px. The final image the same.
I'm using the GD library with PHP.
So my idea was to create a PNG-24 from my original PNG-8, then use color transparency and finally copy the second image into
this new PNG-24. The problem appears in the first step anyway, when going from PNG-24 to PNG-8 with color transparency:
This is to get the original PNG-8 and it's dimensions:
$png8 = imagecreatefrompng($imageUrl);
$size = getimagesize($imageUrl);
Now i create a new PNG and fill it's background with a green color (not present in the images):
$png24 = imagecreatetruecolor($size[0], $size[1]);
$transparentIndex = imagecolorallocate($png24, 0x66, 0xff, 0x66);
imagefill($png24, 0, 0, $transparentIndex);
This is for making the green color transparent:
imagecolortransparent($png24, $transparentIndex);
Then i copy the png8 into the PNG-24:
imagecopy($png24, $png8, 0, 0, 0, 0, $size[0], $size[1]);
So here's the problem: the original PNG-8 looks good, but it has a green border surrounding the shape within the original image. It's difficult to explain really. Seems like some part of the green background is left in the remaining PNG.
What can i do?
thanks in advance
best regards,
Fernando
I had some problems with png transparency before and was able to solve them with this pattern:
// allocate original image to copy stuff to
$img = imagecreatetruecolor(200, 100);
// create second image
$bg = imagecreatefrompng('bg.png');
// copy image onto it using imagecopyresampled
imagecopyresampled($img, $bg, 0, 0, 0, 0, 200, 100, 200, 100);
imagedestroy($bg);
// create third image
// do same routine
$fg = imagecreatefrompng('fg.png');
imagecopyresampled($img, $fg, 50, 50, 0, 0, 50, 50, 50, 50);
imagedestroy($fg);
// output image
imagepng($img);
imagedestroy($img);
I think the only difference between mine and yours is imagecopy() vs. imagecopyresampled(). I seem to remember having problems with that though it was quite a while ago. You can see an example of an image I use this pattern on here: http://www.ipnow.org/images/1/bggrad/bg4/yes/TRANSIST.TTF/8B0000/custombrowserimage.jpg (I allocate a blank image, copy the background image in, copy the overlay with transparency in)