PMView.com

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
> Color/Shade Reducing - missing feature?
Guest_Andreas Kieser_*
post Aug 10 2003, 09:37 AM
Post #1





Guests






It makes a big difference in size in indexed color formats how many colors a picture has. One can see this when switching from 8 to 4 bit (or 2). PMView sometimes reduces the number of colors according to internal tables (it says 6-bit for example).

But: I didn't ever get the hang of willingly reducing the number of colors - say: from 254 or such to say 137 which may preserve an acceptable quality but reduces the needed size to a minimum.

It is doable: one might edit the colors within the palette editor to equal values - PMView will correct the numbers after loading the palette again.

I think that this process could be "automized" and the "quantizing" of colors could be done by algorithms that might well be implemented in the code.

I know that christmas hasn't come yet but .... ;-)))

Regards,

Andreas
Go to the top of the page
 
+Quote Post
Peter
post Aug 11 2003, 04:37 AM
Post #2


Forum Member


Group: Admin
Posts: 671
Joined: 14-March 00
From: Wilmington, North Carolina
Member No.: 3



This feature already exists:

Select "Color->Convert to->256 colors" from the menu bar.
Use the "Number of colors" spinbutton to select the number of colors you want (from 2-256).

Thanks,


--------------------
Peter Nielsen (peter@pmview.com) "If you can dream it, you can do it" JFK.
Go to the top of the page
 
+Quote Post
andreask
post Aug 11 2003, 03:07 PM
Post #3


Forum Member


Group: Members
Posts: 1
Joined: 11-August 03
From: DE/Bavaria
Member No.: 157



Thanks, you're right - I've missed it.

I've made a quick test - a (big) grayscale image with 245 shades. When I try to set up 129 shades the result is 64 shades. (In fact not a bad result, the picture quality is acceptable).

Is this a foreseeable effect? How does it work?

A little lengthy explanation why I did ask: I was forced to Win lately (notebook..) and with this kind of problems I'm still used to Embellish. There's a nice implementation of (visible) color reducing in Embellish: when saving (as) two representations of the picture are shown within a seperate frame and one can fiddle around with save options and see the difference visually and the data related to it (say estimated size etc.).

One can't have it all ...

Regards,

Andreas
Go to the top of the page
 
+Quote Post
Peter
post Aug 14 2003, 07:43 AM
Post #4


Forum Member


Group: Admin
Posts: 671
Joined: 14-March 00
From: Wilmington, North Carolina
Member No.: 3



This is because the color reduction algorithm uses only 6 bits per color (instead of 8).

Usually this is good enough. I have planned to add a full 8-bit reduction, but because noone has requested it (yet), it is not high priority...

Thanks,


--------------------
Peter Nielsen (peter@pmview.com) "If you can dream it, you can do it" JFK.
Go to the top of the page
 
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



Lo-Fi Version Time is now: 24th February 2020 - 09:48 PM