I want get the exact "gray level" of a given image in PHP. I can't understand why I always get [0, 0, 0] as RGB array using imagecolorsforindex. This is my code:
// load
$img = imagecreatefromjpeg("images/white.jpeg");
// to grayscale
imagefilter($img, IMG_FILTER_GRAYSCALE);
// just 1 pixel that describe the whole image
$grayLevel = resize_image($img, 1, 1);
$gray = imagecolorat($grayLevel, 1, 1);
$readble = imagecolorsforindex($grayLevel, $gray);
print_r($readble);
I first load my image (it's a completely white image, so every pixel should be [255, 255, 255] according to this) and then transform it in grayscale. I resize the image to only one pixel that describe the entire image and I get the RGB array. The array is [0, 0, 0].
I can't understand why I always get [0, 0, 0] with images in grayscale, with color. It the 1-pixel technique wrong?
Many thanks
PS: the resize_image works, I've tested it, anyway this is the code: https://pastebin.com/HNDzKq5E
The first pixel in the image exists at (0, 0), not (1, 1). Try changing
$gray = imagecolorat($grayLevel, 1, 1);
to
$gray = imagecolorat($grayLevel, 0, 0);
Related
I have a very frustrating situation. I am using PHP GD for the first time, and it's been a bit of a rollercoaster relationship. Basically, I am trying to merge 2 images, a square one (with a height/width of x) onto a rectangle (with a width of x and a height of y).
The square needs to be centered vertically. But this isn't the issue - I've managed to position it correctly.
Whats happening is, my rectangle is white. My square has a white background, so when the images are merged, it should just look like my asset on a white rectangluar background.
When I merge the image though, GD is for some reason changing my background white rectangle to black - so you can see the white square in the middle, with black "bars" on top and bottom. Can anyone help?
Code is:
//create copy of original image to correct size
imagecopyresized($dst_image, $src_image, 0,0,0,0,$x_width,$x_height,$orig_img_x_width,$orig_img_x_height);
imagejpeg($dst_image, "resized_copy.jpg", 100);
$img = imagecreatetruecolor(1333, 2000);
$white = imagecolorallocate($img, 255, 255, 255);
imagefill ( $img, 0, 0, $white );
imagefilledrectangle($img,0,0,1333,2000, $white);
imagejpeg($img, "rectangle.jpg", 100);
//merge images
$dest2 = imagecreatefromjpeg("rectangle.jpg");
$src2 = imagecreatefromjpeg('resized_copy.jpg');
imagecopymerge($dest2, $src2, 0, 0, 0, -333.5, $x_width, $x_height, 100);
imagejpeg($dest2, "final_image.jpg", 100);
I've tried using imagecopy instead of imagecopymerge, but I get the same result. I'm sure there is a simple explanation, but I cant seem to find it trawling through the php manual.
I've read your question a few times but I'm not convinced I understand exactly what you are trying to achieve so I've made a few assumptions in producing the below code.
For the sake of simplicity I've created a 'square.jpg' test image file like so:
(Note that I've used small image sizes here so I can show them inline.)
// read in the square test image.
$square = imagecreatefromjpeg('square.jpg');
$square_x = imagesx($square); // 100px
$square_y = imagesy($square); // 100px
// create the rectangular image to merge with.
$rectangle = imagecreatetruecolor(100, 200);
$rectangle_x = imagesx($rectangle); // 100px
$rectangle_y = imagesy($rectangle); // 200px
// note that this isn't white, but rather a lovely shade of blue to better
// show the image on the white SO background!
$white = imagecolorallocate($rectangle, 128, 128, 255);
imagefill($rectangle, 0, 0, $white);
// merge the images.
imagecopymerge(
$rectangle,
$square,
0,
($rectangle_y / 2) - ($square_y / 2), // to vertically centre the square.
0,
0,
$square_x,
$square_y,
75 // Just to show the merge clearly; change back to 100 for your usage.
);
imagejpeg($rectangle, 'final_image.jpg', 100);
imagedestroy($rectangle);
imagedestroy($square);
This gives me the following image in final_image.jpg:
I have written a code for merge two images.
My code is:
$rnd = rand("99000", "99999");
$dst_path = "/home/maxioutl/public_html/images/urunler/";
$dst_file_name = "tresim-{$rnd}.jpg";
$dst_file = $dst_path.$dst_file_name;
$dst = imagecreatetruecolor(250, 375);
imagefill($dst, 0, 0, imagecolorallocate($dst, 255, 255, 255));
$src = imagecreatefromjpeg("http://www.goldstore.com.tr/upload/product/raw/3.72925.0332.JPG");
imagecopymerge($dst, $src, 40, 60, 0, 0, 250, 375, 100);
imagejpeg($dst, $dst_file, 90);
Result:
Black background. Where is it?
It's the imagecopymerge($dst, $src, 40, 60, 0, 0, 250, 375, 100); statement that's doing it.
You're passing it the dimensions 250x375, which isn't the watch's actual dimensions. Therefore the merge bounding box continues on and it uses black. You can see this easily if you comment it out because you'll get your white square from the fill like you were expecting.
you need to get the exact dimensions of your watch graphic (i.e. through getimagesize) and pass those to imagecopymerge so it cuts it exactly when it merges.
$arrSize = getimagesize($originalFile);
imagecopymerge($dst, $src, 40, 60, 0, 0, $arrSize[0], $arrSize[1], 100);
The code you wrote superimposes the images. It does not remove the white pixels from the image with the watch.
They are basically overlapped.
You should cycle through both image dimensions and replace each *white pixel with a black pixel or a transparent pixel.
*white pixel may not necessarily mean rgb(255,255,255) you can choose to treat all pixels with rgb(>235,>235,>235) as being "white".
Function imagecreatetruecolor creates completely black image
Taken from here :
imagecreatetruecolor() returns an image identifier representing a
black image of the specified size.
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)
I currently have a script ready that resizes a whole image with GD but I need to get a specific part of an image to display and resize only that specific part.
This is the image:
http://craffy.gdscei.com/enjikaka.png
This is what needs to be displayed, took out the rest with Photoshop:
http://craffy.gdscei.com/enjikakap.png
The final image needs to be 150x150.
This is the script i tried:
<?php
$srcp = imagecreatefrompng("enjikaka.png");
$destp = imagecreate(150, 150);
imagecopyresampled($destp, $srcp, 0, 0, -8, -8, 150, 150, 64, 32);
header('Content-type: image/png');
imagepng($destp);
?>
But this one does not pick the correct part of the image. Can anyone help me here?
Why the (-8, -8)? Those should be the upper left corner of your area to copy. It should be 8, 8. And the last two parameters: (64, 32) are the width and height of your source area. Those should be 8, 8 too.
imagecopyresampled ($destp, $srcp, 0, 0, 8, 8, 150, 150, 8, 8);
I assume here that your source image is built up by 8x8 units. You should check the coordinates in photosop.
I suggest you read the documentation of the function. That shopuld be the first thing you do when things do not go as you expected.
$srcp = imagecreatefrompng("enjikaka.png");
$destp = imagecreate(150, 150);
imagecopy($despt, $srcp, $dst_x , $dst_y , $src_x , $src_y , $src_w , $src_h);
I think you should include this call to imagecopy in your script, which should handle the cropping of the image.