TweakPNG is a low-level utility for examining and modifying PNG image files. It supports Windows XP and higher. In order to make much use of it, you have to be at least familiar with the internal format of PNG files. This is a windows based tool so we need to install a tool called wine to run TweakPNG on Linux.
Installation for wine can be done by executing the following command.
$ sudo apt install wine-stable
TweakPNG executable can be downloaded from here.
Let's open this PNG image in TweakPNG and examine it. Open 64-bit version of TweakPNG using wine. The syntax is as follows.
$ wine tweakpng.exe
Then the following window will be displayed.
Now, if the above cat image is opened in TweakPNG, the following window will be displayed.
For an in-depth understanding on PNG file structure , click here.