PNG image file size/quality using MarvinBeans molconvert

User 48fe63575a

30-09-2009 12:15:08

Hi,



We are testing png image generation techniques and have found the quality and performance of Molconvert to be excellent.


We have noticed that the actual file size created can be quite high when compared to alternate tools.  We can see that the images - even if created in mono with transparent background are getting created with a colour depth of 16 million (24 bit?).


Is there a way to change this color depth as an option supplied to molconvert?  I can see the PNG option for b24 and b32 - but that makes the file size even bigger.  For a structure like the one attached, an image for web use would be fine at 16 (4 bit?).  This could reduce the file size by up to 90% - which is a bonus when loading images of millions of records.


Do you have any suggestions as to reduce the colour depth?  Is it a PNG limitation?  Should we try to export to a different format first and then convert to a PNG?


Many thanks.


 

ChemAxon 7c2d26e5cf

30-09-2009 21:28:39

Hi,


Currently Marvin's png export support only 24 and 32 bit color depth. The defalut compression level is 9 (maximum). Currently, the only way to reduce the size of the image is decreasing the image quality: switching of antialiasing. You can do it by giving the "noantialias" image export parameter.


Anyway, we consider your request to improve our PNG export with supporting lower color depth (4 or 8) in the future.

ChemAxon 7c2d26e5cf

30-09-2009 21:46:19

Is it a PNG limitation?  Should we try to export to a different format first and then convert to a PNG?



I think PNG is an effective/economic raster image format. I can not recommend better.


But you can try to use an external tool to convert Marvin image/png into a new png that support 4 or 8 bit color depth.