Help needed for PNG-8 to bmp with alpha

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mixkef
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Help needed for PNG-8 to bmp with alpha

Post by mixkef » 2017-12-26T05:02:20-07:00

Hi

I created one png-8 image with fireworks with alpha transparency .As i check about 160 colors in my palette have alpha channel 0<alpha<255 .The rest have alpha=255 .So far so good. Now i want to keep that palette and make a file BMP-8 Paletted and rle compressed.
Is this possible ?. If so what is the syntax ?.As i understand it's not standard to bmp format .Is there another image format without heavy compression i could use ?.
Thank's for any help you can provide !!!.

snibgo
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Re: Help needed for PNG-8 to bmp with alpha

Post by snibgo » 2017-12-26T07:07:37-07:00

Why do you want a BMP file with alpha in the palette? Microsoft documentation is contradictory about whether this is allowed, so I expect some software will ignore the alpha. (See https://en.wikipedia.org/wiki/BMP_file_format )

I don't think IM can make BMP files with alpha in the palette.
mixkef wrote:Is there another image format without heavy compression i could use ?
I suggest PNG if your image is a graphic, or TIFF (with Zip or LZW compression) if your image is a photo.
snibgo's IM pages: im.snibgo.com

mixkef
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Re: Help needed for PNG-8 to bmp with alpha

Post by mixkef » 2017-12-26T07:23:44-07:00

Hi,
Thank's for your reply.I have an embedded device that displays a number over a image backgound . Numbers don't show nice without Alpha (old story ).
On the other side i want <24 ms response time in drawing a number 160x280 pixels which is impossible for my mcu to handle with any type of PNG or even GIF compression .
So it seems i have to write one converter to do that . I saw so much potential in ImageMagick so i though somebody must have done it already.

snibgo
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Re: Help needed for PNG-8 to bmp with alpha

Post by snibgo » 2017-12-26T07:34:28-07:00

Do you need compression? If speed is critical, don't compress.
snibgo's IM pages: im.snibgo.com

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