IMagick检查亮度图像 [英] IMagick check lightness image

问题描述

我需要能够在图像中自动编写一些文本。根据图像的亮度，脚本必须写成白色或黑色。

I need to be able to write some text automatically inside an image. According to the image lightness, the script must write in white or black.

那么如何使用Imagick检查图像的亮度/暗度？

So how do I check the lightness/darkness of an image with Imagick?

推荐答案

你可以这样做：

// Load the image
$imagick = new Imagick("image.jpg");
// convert to HSL - Hue, Saturation and LIGHTNESS
$imagick->transformImageColorspace(imagick::COLORSPACE_HSL);
// Get statistics for the LIGHTNESS
$Lchannel = $imagick->getImageChannelMean(imagick::CHANNEL_BLUE);
$meanLightness = $Lchannel['mean']/65535;
printf("Mean lightness: %f",$meanLightness);

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如果你想做下色文本，请根据Fred's建议，您可以在PHP中执行以下操作：

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If you want to do undercoloured text, per Fred's suggestion, you can do that in PHP with:

$image = new Imagick("image.jpg");
$draw  = new ImagickDraw();
$draw->setFillColor('#ffffff');
$draw->setFontSize(24);
$draw->setTextUnderColor('#ff000080');
$image->annotateImage($draw,30,50,0,"Undercoloured Text");
$image->writeImage('result.jpg');

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