原因是新版的libpng增强了检查，发出警告。此警告可以忽略。
若要消除此警告则要使用v4的色彩配置。
GIMP sRGB v4 色彩配置，修改当前图片的色彩配置，设为默认。
sRGB profiles
On this page you will find several different types of sRGB profiles, with information about their intended use.
sRGB v4 Preference
sRGB v4 Appearance
sRGB v2
sRGB v4 Preference
The sRGB v4 ICC preference profile is a v4 replacement for commonly used v2 sRGB profiles. It gives better results in workflows that implement the ICC v4 specification. It is intended to be used in combination with other ICC v4 profiles.
The advantages of the new profile are:
More pleasing results for most images when combined with any correctly-constructed v4 output profile using the perceptual rendering intent.
More consistently correct results among different CMMs using the ICC-absolute colorimetric rendering intent.
Higher color accuracy using the media-relative colorimetric intent.
A typical use case would be to print sRGB images captured with a digital still camera. In this case a user could open the image in Adobe® Photoshop®, assign the sRGB v4 profile as shown in Figure 1. Adobe® Photoshop® is either a registered trademark or trademark of Adobe Systems Incorporated in the United States and/or other countries.
解决方法：
下载ImageMagick：https://imagemagick.org/script/download.php#windows
然后将图片打开再另存即可。
批量执行
也可以通过脚本转换，同样需要上面的工具，注意将fn的值修改为程序安装的路径
@echo off
echo ImageMagick fix libpng warning: iCCP: Not recognizing known sRGB profile ......
echo Search PNG in subdirs and process ...
set fn=C:\soft\ImageMagick-7.0.-Q16\convert.exe
for /f "tokens=*" %%i in ('dir/s/b *.png') do "%fn%" "%%i" -strip "%%i"
pause
然后将该bat脚本放在图片目录下
双击执行即可
所有图片就已经替换完毕了！
参考：
https://www.cnblogs.com/Esperanto/p/8044032.html
https://zhidao.baidu.com/question/1175819353197087339.html
https://blog.csdn.net/u010212648/article/details/82191419