HDCD decoding should be enabled automatically if the HDCD decoder is placed in the components folder. The bit depth value in file properties does not show the bit depth of the decoded audio signal.
When the component is installed you can select the files and do "right-click > Utilities > Scan for HDCD tracks". It will show the scan results in a new window.
You can add a HDCD column to playlists and a HDCD status text to the Status Bar:
I use this code for the HDCD column (in Columns UI):
$if(%__hdcd%,HDCD ,)
and this for the status line:
$if(%ispaused%,Paused,Playing) | %codec% | %bitrate% kbps | %samplerate% Hz | $caps(%channels%) | %playback_time%[ / %length%][ |$if(%__hdcd%,' 'HDCD '('gain: %__hdcd_gain%',' peak extension: %__hdcd_peak_extend%')',)]
The HDCD status will be displayed during playback.
Perhaps someone else can help you with "HDCD png".