Preserve background color ?

[Bingo]

Hi all !

I'd like to use nconvert to convert EPS files (with a transparent background by design) to PNGs (256 colors, indexed).
If I try :
nconvert -o my.png -out png -dpi 140 my.eps
it works fine : I get a nice png with a white background.
But if I try :
nconvert -o my.png -out png -dpi 140 -colors 256 my.eps
the resulting file has a bluish background color (248,252,249).

The original file is almost only tranparent with some lines and texts (it's a map, actually), and I really need to preserve a white background.
Is there a way to achieve this ?

Thanks for helping !

[xnview]

Hi all !

I'd like to use nconvert to convert EPS files (with a transparent background by design) to PNGs (256 colors, indexed).
If I try :
nconvert -o my.png -out png -dpi 140 my.eps
it works fine : I get a nice png with a white background.
But if I try :
nconvert -o my.png -out png -dpi 140 -colors 256 my.eps
the resulting file has a bluish background color (248,252,249).

The original file is almost only tranparent with some lines and texts (it's a map, actually), and I really need to preserve a white background.
Is there a way to achieve this ?

No sorry, it's ghostscript

[Bingo]

Okay.
Now if I convert to PNG (16m colors), and then reprocess the image to reduce colors to 256, can I keep my white... white ?

[xnview]

Okay.
Now if I convert to PNG (16m colors), and then reprocess the image to reduce colors to 256, can I keep my white... white ?

Try, if you have a lot of white, white will be white

[Bingo]

Okay.
Now if I convert to PNG (16m colors), and then reprocess the image to reduce colors to 256, can I keep my white... white ?

Try, if you have a lot of white, white will be white

I tried, but white is not white.
I really have a lot of white though ! I'd say around 95% maybe.

[xnview]

Okay.
Now if I convert to PNG (16m colors), and then reprocess the image to reduce colors to 256, can I keep my white... white ?

Try, if you have a lot of white, white will be white

I tried, but white is not white.
I really have a lot of white though ! I'd say around 95% maybe.

Could you send me the PNG 16m?

[Bingo]

Of course.
I'll send it to you tomorrow morning.

[Bingo]

OK, pm sent with link to the image.
Thanks for helping Pierre.

[Bingo]

Pierre,
Have you found something new about this matter ?

Arnaud

[xnview]

Have you found something new about this matter ?

Do you have received my reply by pm?

[Bingo]

Do you have received my reply by pm?

Yes I have.
You noticed that their was no problem when "-dither" was used, but I was wondering whether you had found a solution for non-dithered conversions ?

Best regards,
Arnaud

[Bingo]

Pierre,

Are you planning on releasing a new build of nconvert ?
I am still in a test period, but I have to write batch jobs, and I would have liked to know whether I could write nconvert command lines, or if I had to write them using mogrify (which works but is horribly slow!!!).

Best regards,
Arnaud

[xnview]

Are you planning on releasing a new build of nconvert ?
I am still in a test period, but I have to write batch jobs, and I would have liked to know whether I could write nconvert command lines, or if I had to write them using mogrify (which works but is horribly slow!!!).

But with the -dither, all is ok, no?

[Bingo]

But with the -dither, all is ok, no?

Yes, but the output is... dithered !
I do not want dithering in the output images, I need plain colors.

[xnview]

But with the -dither, all is ok, no?

Yes, but the output is... dithered !
I do not want dithering in the output images, I need plain colors.

Yes, right. There is a problem because when i quantize picture, i reduce bits per component, so after white is no more white
You can try with other software, you'll have same result.
But do you have same result with ImageMagick?