Save Transparent PNG image. . . .

[Satish S.R]

Hi there,

 

     I am trying to save png image's from mapinfo using mapbasic code.The PNG image's which i am getting like BMP Opacity is 100% but i want it 0%.

     Please anyone help me - how to save transparent(alpha) PNG image.

 

Thank you

Satish S.R

[Warren Vick]

Hello Satish,

 

I think you will need to post-process the image, especially if you want to vary the opacity. Perhaps output one PNG with the full colours you wish to use, then another in greyscale to represent the opacity. Then, use any number of commercial and open source tools/library to bring in the greyscale image and integrate it as the alpha channel for the colour image.

 

Regards,

Warren Vick

Europa Technologies Ltd.

http://www.europa.uk.com

[Satish S.R]

Hi,

 

   The Png image which i am getting like Bmp image (the mapper window white color is also coming in PNG).I need white color be a transparent.

 

Thankyou

Satish

[Ed]

Hi,

I assume this is for the transparent PNG usage in Google maps or other
tools.

Generally Mapinfo only export in standard PNG format without alpha
channel tranparency.

To have transparency (alpha channel) in the PNG, it needs to be PNG128
or 8 bit. 8 bit is far more efficient and smaller in size. I use the
process of saving a macro in Adobe photoshop to batch convert a group
of PNGs to alpha channel transparency, and then I run it through
PNGGauntlet http://brh.numbera.com/software/pnggauntlet/ to convert to
8 bit.

If you want a document on creating the alpha transparency in GIMP, let
me know, I have one here. But, you can't do the batch change in GIMP
as easily as Adobe Photoshop.

Not perfect, but it works fine!

regards
Ed

On Nov 13, 10:15 am, "Satish S.R" <satish....@gmail.com> wrote:
> Hi,
>
>    The Png image which i am getting like Bmp image (the mapper window white
> color is also coming in PNG).I need white color be a transparent.
>
> Thankyou
> Satish
>
> On Fri, Nov 13, 2009 at 2:39 PM, Warren Vick <wv...@europa.uk.com> wrote:
> >  Hello Satish,
>
> > I think you will need to post-process the image, especially if you want to
> > vary the opacity. Perhaps output one PNG with the full colours you wish to
> > use, then another in greyscale to represent the opacity. Then, use any
> > number of commercial and open source tools/library to bring in the greyscale
> > image and integrate it as the alpha channel for the colour image.
>
> > Regards,
>
> > Warren Vick
>
> > Europa Technologies Ltd.
>
> >http://www.europa.uk.com
>

> > *From:* mapi...@googlegroups.com [mailto:mapi...@googlegroups.com] *On
> > Behalf Of *Satish S.R
> > *Sent:* 13 November 2009 5:44 AM
>
> > *To:* mapi...@googlegroups.com
> > *Subject:* [MI-L] Save Transparent PNG image. . . .

[Warren Vick]

Hello Satish,

 

If you want a single colour to be transparent and your colour palette is 8-bit, you can do this with PNG. However, for varying opacity, you will need 24-bit colour and 8-bit alpha. Again, all this can only be done post process as I don't think Pro has any native support.

<br