N:.A | Size KB
V: $ifgreater(%_cover_size%,0,%_covers% | $fmtnum($div(%_cover_size%,1024))' KB','-')
S:.%_covers% %_cover_size% %title%
N: [ ]
It basically displays a '-' if no artwork is present but if there is then it shows in the format 'Number of covers | Size KB'.
I have Numeric check-box 'unticked' as I feel it looks better that way. It's all down to personal preference and all that!...
And, the Sort by column sorts by the amount of covers followed by the size as shown in the attached screen-shots. You can change this around if your prefer sorting the other way around. The %title% then sorts them with there title. The option numerical [ ] box must be unchecked for this to take effect.
Filtering in kb
Now to filter them. Good thing to note is probably the reason some of your music players art doesn't show is because the file size is beyond its capability's and you should do some tests to prove it or consult with the manufacturer. I personally have an iPod Classic which has artwork on it up to 200kb without any problems. I haven't tested beyond this but most of my artwork is either 1000px or 500px sq. which should look good at 200kb either way.
Examples of filters are:
Please note adding 'kb' is not documented in the help files but still works.
All files that do not contain cover art
%_covers% IS ""
All files with cover art larger than 200kb
"$div(%_cover_size%,1024)" GREATER 200'kb'
All files with cover art less than 50kb
"$div(%_cover_size%,1024)" LESS 50'kb'
All files with cover art larger than 200kb OR All files with cover art less than 50kb
"$div(%_cover_size%,1024)" GREATER 200'kb' OR "$div(%_cover_size%,1024)" LESS 50'kb'
I hope you have picked up something useful here to use.