Images have to be lossless compressed to save many bytes of data and thus bandwidth. This speeds up the download time of your website. But, how do we optimize images for the web? Or, what if I have hundreds of images that needs optimization? Let's optimize and lossless compress images in bulk using OptiPNG, read on.
Optimize images for the web in bulk with OptiPNG
In this post we optimize PNG images as example. The same goes for lossless compressing and optimizing JPEG images, you only need another tool (jpegtran or jpegoptim).
Google PageSpeed Insights already mentions the tools, we only have to download and use them.
So, go ahead and download OptiPNG. There is no installation required, it's a run once executable for the command line.
If you are familiar with the command line, for example on Windows 7 and higher, you can very easily execute OptiPNG with its default settings on all your PNG files in a directory:
D:\Dev\sites>
FOR /F %I in ('dir /b/s *.png')
do @c:\optipng-0.7.4-win32\optipng.exe %I
This will lossless compress and optimize all PNG images in bulk, found within d:\dev\sites\ and recursively into sub directories, making your images and website-footprint smaller, resulting in a faster download of your website.
Find more website optimization tips at Website optimization: minify JavaScript, CSS and compress images.
OptiPNG: lossless compressing images on the fly
The following command lossless compresses all PNG files recursively, from within my content directory:
FOR /F %I in ('dir /b/s *.png') DO @C:\Temp\optipng-0.7.5-win32\optipng.exe -o5 %I