Image tinting with the GD library

[nicky77]

Hi,

I'm trying to set up a range of preset image tints using the GD library. I tried with ImageMagick and only managed to find one function which gave me one tint (using Imagick::sepiaToneImage()) - ended up pretty disappointed with Imagick due to the lack of documentation. Anyway, I've been messing about all day trying to get the right formula for these tints but am still pretty stuck.

Basically, I want to be able to take any image and allow CMS users to be able to select their desired tint using a radio button. The tint applied has to work with whatever image has been uploaded - this might mean I should convert everything to greyscale before applying the colour tint? The tints I want to apply are really saturations and hues, and I've not been able to get this effect with the code i have below.

If anyone has experience of doing this type of thing, any help would be appreciated as i'm still trying to get to grip with the GD functions and have a long way to go!

Here is what I have at the moment:

function img_tint($path_image, $red, $green, $blue)
{
    $im = imagecreatefromjpeg($path_image);
    $pixel = array();
       
    $n_im = imagecreatetruecolor(imagesx($im),imagesy($im));
    $fond = imagecolorallocatealpha($n_im, 255, 255, 255, 0);
    imagefill($n_im, 0, 0, $fond);
   
    for($y=0;$y<imagesy($n_im);$y++)
    {
        for($x=0;$x<imagesx($n_im);$x++)
        {
            $rgb = imagecolorat($im, $x, $y);           
            $pixel = imagecolorsforindex($im, $rgb);
           
            $r = min(round($red*$pixel['red']/169),255);
            $g = min(round($green*$pixel['green']/169),255);
            $b = min(round($blue*$pixel['blue']/169),255);
            $a = $pixel['alpha'];           
           
            $pixelcolor = imagecolorallocatealpha($n_im, $r, $g, $b, $a);
           
            imagealphablending($n_im, TRUE);
            imagesetpixel($n_im, $x, $y, $pixelcolor);
        }
    }
          header("Content-type: image/jpeg");
       imagejpeg($n_im, time().$path_image.'.jpg');
       imagedestroy($n_im);
}

//img_tint("neyo.jpg", 167, 59, 62); //too red
//img_tint("neyo.jpg", 57, 0, 12); //too dark and red
//img_tint("neyo.jpg", 15, 200, 32); //too green
//img_tint("neyo.jpg", 15, 100, 32); //bit dark and still too green
//img_tint("neyo.jpg", 15, 50, 132); //too blue
//img_tint("neyo.jpg", 15, 10, 32); //far too dark
//img_tint("neyo.jpg", 35, 30, 62); //still too dark, bit purple
img_tint("neyo.jpg", 15, 50, 22); 

[Rubble]

You could ask a question about Imagick on the Imagemagick forum: http://redux.imagemagick.org/discourse-server/index.php

I use imagemagick with the command line and php as there are a lot more options.

Anthony has pages of examples here http://www.imagemagick.org/Usage/ and there must be an example of what you want to do.

[adstiger]

I have found a good tutorial:

http://www.adguru.org/php-mysql-f15-...al-t24205.html

[nicky77]

Thanks guys - you're right i should take this to the ImageMagick forums. @rubble - yes i'll just use ImageMagick with PHP from the command line instead of using the Imagick wrapper

[Rubble]

Can you get the examples working from the Imagemagick forum Nicky77?

[nicky77]

Hey Rubble - i actually tried to post a reply on the ImageMagick forum earlier but there was a problem with the site and the page kept going blank.

Anyway, I played around with fmw's suggestions and those in the usage section on the website and managed to get the range of tints i was looking for. To achieve a consistent tint, i had to convert to greyscale first, before applying the tint and HSB.

I wasn't too sure if there was a better way of writing the following command though, which i broke down into 2 statements?

 exec("convert $original_image -colorspace Gray $new_image; convert $new_image -fill LightGoldenrod2 -tint 100 -modulate 125,75,100 $new_image");

[Salathe]

Hi, glad to see you've got something working with ImageMagick. Is there any reason why the GD tinting with imagefilter won't work for you?

[Rubble]

Supposed to be working so have to be quick!

Not as easy as it should be but try:

$array=array();
echo "<pre>";
exec("convert $original_image -colorspace Gray  miff:- | convert -fill LightGoldenrod2 -tint 100 -modulate 125,75,100 - $new_image 2>&1", $array); 
echo "<br>".print_r($array)."<br>";
echo "</pre>"; 

I have put some code in for error reporting; you can remove it when everything is working.
This code may depend on your type of shell.

[nicky77]

@Rubble - just tested the code you provided and it achieves the same tint effect! is it more preferable to use the command syntax you provided (using miff) than the 2 sequential statements i had initially? both your suggestion and my code both have the desired effect anyway

@salathe - i spent a lot of time trying to use the GD library to get the tint effects i was looking for but didn't really come close. I'm sure it probably can be done, i just couldn't get it right so i gave up the ghost and decided to try imagemagick instead.

[Rubble]

The code I provided uses a miff format which is an Imagemagick format and no compression which is better than jpg.
The miff:- saves the image in the memory so no tempory files.
The | "pipes" the output from the first part of the code to the second; something to do with Linux ?

Anyway not quite sure exactly how it all works but it does. We should have been able to get the same result with something like:

exec("convert \( $original_image -colorspace Gray \) -fill LightGoldenrod2 -tint 100 -modulate 125,75,100 $new_image"); 

But that does not work !

[Salathe]

@salathe - i spent a lot of time trying to use the GD library to get the tint effects i was looking for but didn't really come close. I'm sure it probably can be done, i just couldn't get it right so i gave up the ghost and decided to try imagemagick instead.

Given the ImageMagick examples post in this thread, it's perfectly reasonable to achieve the same effect through GD. If you're willing to pull back that ghost for a while, you might try something along these lines:

imagefilter($im, IMG_FILTER_GRAYSCALE);
// Apply tint (values range from -255 to +255 for r, g, b and 0 to 127 for a);
imagefilter($im, IMG_FILTER_COLORIZE, 0, -15, -90, 30);
imagefilter($im, IMG_FILTER_BRIGHTNESS, 40);
imagefilter($im, IMG_FILTER_CONTRAST, -20); 

[nicky77]

Given the ImageMagick examples post in this thread, it's perfectly reasonable to achieve the same effect through GD. If you're willing to pull back that ghost for a while, you might try something along these lines:

imagefilter($im, IMG_FILTER_GRAYSCALE);
// Apply tint (values range from -255 to +255 for r, g, b and 0 to 127 for a);
imagefilter($im, IMG_FILTER_COLORIZE, 0, -15, -90, 30);
imagefilter($im, IMG_FILTER_BRIGHTNESS, 40);
imagefilter($im, IMG_FILTER_CONTRAST, -20); 

@Salathe - this works perfectly too! I'll probably stick with the ImageMagick code i have which is working fine and seeing as i now have ImageMagick installed on my server. But it's good to know how to achieve this effect with GD too, in case i ever need to do this again on a server where i can't install ImageMagick. Many thanks to you and Rubble for your help

[adstiger]

what is the version of ImageMagick that you have?