gd-png: fatal libpng error: zlib error

The third parameter is for the quality of the image. 正在生成的圖像是可能的最高質量的JPEG圖像是一個範圍從0（最低質量，最小的文件大小）到100（最高質量，最大文件大小）。 The images being generated are the highest quality possible which for JPEG images is a range from 0 (lowest quality, smallest file size) to 100 (highest quality, largest file size).

出現這一錯誤的原因是爲ImagePNG職能的質量範圍從0到9的任何外部不會工作。 The reason for the error is that the quality range for the ImagePNG function is from 0 to 9 and anything outside that won't work. 所以，簡單地將值更改爲0到9之間，錯誤會自行消失。 So simply change the value to between 0 and 9 and the error will go away.