PHP image pixel image?

Question

I need to make this effect using php. I know that IMG_FILTER_PIXELATE in PHP image filters. But do I need it to be smoother and more embossed? as in this image:

This effect will cause any image uploaded by the user to become pixelated and the edge of the image will turn red (I know IMG_FILTER_EDGEDETECT, but I don't know how to use it to change the color of the edge).

I do not know how to do that.

Answer 1

Since the last answer was theoretical and seemed to be insufficient, I created a practical example:
Note. This is far from an “ideal” and ideal pixel effect function, but it does the job. Feel free to edit it to suit your needs.

<?php /* Function to make pixelated images * Supported input: .png .jpg .jpeg .gif * * * Created on 24.01.2011 by Henrik Peinar */ /* * image - the location of the image to pixelate * pixelate_x - the size of "pixelate" effect on X axis (default 10) * pixelate_y - the size of "pixelate" effect on Y axis (default 10) * output - the name of the output file (extension will be added) */ function pixelate($image, $output, $pixelate_x = 20, $pixelate_y = 20) { // check if the input file exists if(!file_exists($image)) echo 'File "'. $image .'" not found'; // get the input file extension and create a GD resource from it $ext = pathinfo($image, PATHINFO_EXTENSION); if($ext == "jpg" || $ext == "jpeg") $img = imagecreatefromjpeg($image); elseif($ext == "png") $img = imagecreatefrompng($image); elseif($ext == "gif") $img = imagecreatefromgif($image); else echo 'Unsupported file extension'; // now we have the image loaded up and ready for the effect to be applied // get the image size $size = getimagesize($image); $height = $size[1]; $width = $size[0]; // start from the top-left pixel and keep looping until we have the desired effect for($y = 0;$y < $height;$y += $pixelate_y+1) { for($x = 0;$x < $width;$x += $pixelate_x+1) { // get the color for current pixel $rgb = imagecolorsforindex($img, imagecolorat($img, $x, $y)); // get the closest color from palette $color = imagecolorclosest($img, $rgb['red'], $rgb['green'], $rgb['blue']); imagefilledrectangle($img, $x, $y, $x+$pixelate_x, $y+$pixelate_y, $color); } } // save the image $output_name = $output .'_'. time() .'.jpg'; imagejpeg($img, $output_name); imagedestroy($img); } pixelate("test.jpg", "testing"); ?> 

This is an example of a function for creating a pixel effect on images. Here are examples of how to use this function:
Original:

Pixelated 5px:

Pixelated 10px:

Pixelated 20px:

Answer 2

Thanks for your reply. I used your function and added another loop to change the color of the outer pixel of the squares using a function called imagelinethick at http://www.php.net/manual/en/function.imageline.php . So it became:

 <?php $image = imagecreatefromjpeg('Penguins.jpg'); $imagex = imagesx($image); $imagey = imagesy($image); $pixelate_y=10; $pixelate_x=10; $height=$imagey; $width=$imagex; for($y = 0;$y < $height;$y += $pixelate_y+1) { for($x = 0;$x < $width;$x += $pixelate_x+1) { // get the color for current pixel $rgb = imagecolorsforindex($image, imagecolorat($image, $x, $y)); // get the closest color from palette $color = imagecolorclosest($image, $rgb['red'], $rgb['green'], $rgb['blue']); imagefilledrectangle($image, $x, $y, $x+$pixelate_x, $y+$pixelate_y, $color); } } for($y = 0;$y < $height;$y += $pixelate_y+1) { for($x = 0;$x < $width;$x += $pixelate_x+1) { //make a border line for each square $rgb = imagecolorsforindex($image, imagecolorat($image, $x, $y)); $color = imagecolorclosest($image, 123, 123, 123); imagelinethick($image, $x, $y, $x, $y+$pixelate_y, $color, 1); imagelinethick($image, $x, $y, $x+$pixelate_x, $y, $color, 2); } } function imagelinethick($image, $x1, $y1, $x2, $y2, $color, $thick = 1) { /* this way it works well only for orthogonal lines imagesetthickness($image, $thick); return imageline($image, $x1, $y1, $x2, $y2, $color); */ if ($thick == 1) { return imageline($image, $x1, $y1, $x2, $y2, $color); } $t = $thick / 2 - 0.5; if ($x1 == $x2 || $y1 == $y2) { return imagefilledrectangle($image, round(min($x1, $x2) - $t), round(min($y1, $y2) - $t), round(max($x1, $x2) + $t), round(max($y1, $y2) + $t), $color); } $k = ($y2 - $y1) / ($x2 - $x1); //y = kx + q $a = $t / sqrt(1 + pow($k, 2)); $points = array( round($x1 - (1+$k)*$a), round($y1 + (1-$k)*$a), round($x1 - (1-$k)*$a), round($y1 - (1+$k)*$a), round($x2 + (1+$k)*$a), round($y2 - (1-$k)*$a), round($x2 + (1-$k)*$a), round($y2 + (1+$k)*$a), ); imagefilledpolygon($image, $points, 4, $color); return imagepolygon($image, $points, 4, $color); } header("Content-Type: image/JPEG"); imageJPEG($image, "", 75); ?> 

The result is as follows: http://www.flickr.com/photos/ 52700219@N06 / 6759029339 /

But I think that it still needs to be improved to make it smoother.

Answer 3

Here theoretically:
You have an image:

RGBRGBRGBRGB
GBRGBRGBRGBR
GBRGBRGBRRGB
BGRGBGRGGRBG

Take the color of the first pixel and set the same color for the square of the following pixels (both on the right and on the right). Then take the color of the 5th pixel (since the 4 at the beginning have the same color). If you are finished for the first line, go down 3 lines and start again.

So you get:
RRRRGGGBBBB
RRRRGGGBBBB
RRRRGGGBBBB
RRRRGGGBBBB

In PHP, you can use the following functions: http://php.net/manual/en/function.imagecolorat.php to select a pixel color
http://php.net/manual/en/function.imagecolorset.php to set the pixel color
http://php.net/manual/en/function.imagesx.php get image width
http://php.net/manual/en/function.imagesy.php get image height

use for loops through image pixels

Answer 4

This is my attempt to solve the problem.

You can resize the pixel block, and you can apply blur, which softens the effect on high-contrast images. It can be slow on large images with small pixel block sizes though.

The scripts store the colors of the corresponding pixels in the array. Then it reliefs the image, changes the contrast as necessary, pixelates the image using the imagefilter () function, and then (if the tile gain is set) reliefs again (this increases the 3D effect on the final tiles). If blurring is required, the script applies Gaussian blurring. The script then draws the filled squares using a color array to create a colorful pixelated effect within the borders of the relief tile.

 function pixelatemboss($image,$blockwidth=10,$blur=5,$tileenhance="true",$contrast=0,$negate="true") { if($blockwidth>1) { imagefilter($image,IMG_FILTER_CONTRAST,$contrast); for($x=1;$x<imagesx($image);$x=$x+$blockwidth) { for($y=1;$y<imagesy($image);$y=$y+$blockwidth) { $color[$x][$y]=imagecolorat($image,$x,$y); } } imagefilter($image,IMG_FILTER_EMBOSS); imagefilter($image,IMG_FILTER_CONTRAST,$contrast); imagefilter($image,IMG_FILTER_PIXELATE,$blockwidth,false); if($tileenhance=="true") { imagefilter($image,IMG_FILTER_EMBOSS); } for($b=0;$b<$blur;$b++) { imagefilter($image,IMG_FILTER_GAUSSIAN_BLUR); } for($x=1;$x<imagesx($image);$x=$x+$blockwidth) { for($y=1;$y<imagesy($image);$y=$y+$blockwidth) { $rgb=$color[$x][$y]; $r = ($rgb >> 16) & 0xFF; $g = ($rgb >> 8) & 0xFF; $b = $rgb & 0xFF; $col=imagecolorallocate($image,$r,$g,$b); imagefilledrectangle($image,$x,$y,$x+($blockwidth-2),$y+($blockwidth-2),$col); } } } return $image; } 

Answer 5

Note for php 5.4 and above you need to use:

 imageJPEG($image, NULL, 75); 

You can no longer specify NULL using a double quote (for example, this example):

 imageJPEG($image, "", 75);