php 中的图片压缩
现在我想压缩图片,比如说640x480 的图片 现在存储的时候是 600k 我想实现压缩成 640x 480 的480k 大小的图片 这个能实现吗? 如果这样压缩图片会不会损坏?具体要怎么做?急求?????
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降低图片的像素就可以了,可能存在的问题就是图片的显示效果与原图的效果存在色差,存在疵点。
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可以用gd库生成缩略图
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<br /><br /><?php<br />//创建一个压缩包<br />$zp = gzopen("1.gz", "wb");<br />//获取待压缩的数据<br />$string = file_get_contents("com.html");<br />//最大化压缩数据<br />$compress_string = gzcompress($string, 9);<br />//将压缩数据写入压缩包<br />gzwrite($zp, $compress_string, strlen($compress_string));<br />gzclose($zp);<br />?><br /><br />
图片压缩是一样的
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參考:http://blog.csdn.net/fdipzone/article/details/9316385
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不可以!
把 640x 480 600k 压缩成 640x 480 480k,那么去掉的 120k 必然带走了1/5 的图片数据,导致图片质量下降
除非你的原始图片是位图方式(BMP,TIFF)的,但是
gif 是无损压缩,但只有 256 种颜色(即会丢失色彩信息)
jpeg 是有损压缩,显然有损两字已经很好地说明问题了
png 虽是无损压缩,但若是 256色 的,显然是丢失了色彩信息,而真彩的又等于没压缩
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降低quality试试。

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