Magento resize() 图像质量:肮脏的白色背景

问题描述

我有一个客户对他们的产品缩略图在 Magento 上的呈现方式非常不满意.

I have a client who is seriously unhappy with the way their product thumbnails are rendering on Magento.

狡猾的外表在两个帐户中很明显:

The dodgy appearance is noticeable on two accounts:

• 有一个肮脏的白色背景，有很浅的灰色水平线
• 其次，颜色损失非常轻微(失去对比度和饱和度).

我已经删除了所有压缩，将所有质量设置为 100%，刷新了图像缓存，进行了多次试验、损坏和修复，但似乎没有任何效果.

I have removed ALL compression, set ALL quality to 100%, flushed image cache, experimented, broken, and fixed it all dozens of times, and nothing seems to work.

这个版本的 Magento 是 ver.1.4.2.0

This version of Magento is ver. 1.4.2.0

这里有没有人遇到同样的问题，如果有，您是否设法解决了这个问题?

Is anyone out here experiencing the same problems, and if so have you managed to fix it?

推荐答案

问题与lib/Varien/Image/Adapter/Gd2.php里面的resize函数中的php函数imagecopyresampled有关，存在一些舍入问题发生平滑调整大小的图像.

The problem has to do with the php function imagecopyresampled in the resize function inside lib/Varien/Image/Adapter/Gd2.php, there are some rounding issues that occur to make a smoothly resized image.

我的解决方案是在调整图像大小后，将图像中任何非常浅的灰色像素更改为纯白色.为此，首先将 lib/Varien/Image/Adapter/Gd2.php 复制到 app/code/local/Varien/Image/Adapter/Gd2.php

My solution is to simply change any very light grey pixels in the image to pure white after the image has been resized. To do so first copy lib/Varien/Image/Adapter/Gd2.php to app/code/local/Varien/Image/Adapter/Gd2.php

接下来在resize函数中找到以下代码(约312行)

Next find the following code inside the resize function (around line 312)

// resample source image and copy it into new frame
imagecopyresampled(
    $newImage,
    $this->_imageHandler,
    $dstX, $dstY,
    $srcX, $srcY,
    $dstWidth, $dstHeight,
    $this->_imageSrcWidth, $this->_imageSrcHeight
);

然后在下面添加以下代码:

Then add the following code underneath:

// Clean noise on white background images
if ($isTrueColor) {
    $colorWhite = imagecolorallocate($newImage,255,255,255);
    $processHeight = $dstHeight+$dstY;
    $processWidth = $dstWidth+$dstX;
    //Travel y axis
    for($y=$dstY; $y<($processHeight); ++$y){
        // Travel x axis
        for($x=$dstX; $x<($processWidth); ++$x){
            // Change pixel color
            $colorat=imagecolorat($newImage, $x, $y);
            $r = ($colorat >> 16) & 0xFF;
            $g = ($colorat >> 8) & 0xFF;
            $b = $colorat & 0xFF;
            if(($r==253 && $g == 253 && $b ==253) || ($r==254 && $g == 254 && $b ==254)) {
                imagesetpixel($newImage, $x, $y, $colorWhite);
            }
        }
    }
}

从 Magento 中的缓存管理中刷新图像缓存，您应该为新显示器提供更好的图像.执行此操作时需要注意的事项很少，第一次再次生成图像时性能会有所下降，并且由于去除了非常浅的灰色，带有阴影的图像可能具有更清晰的边缘.

Flush the images cache from the Cache management in Magento, and you should have nicer images for the new displays. Few things to note when implementing this, there is a small performance hit the first time you generate the images again, and images with shadows may have sharper edges as the very light greys have been removed.

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