Method Image.GIF.encode_trans()

Method encode_trans

string encode(object img)
string encode(object img, int colors)
string encode(object img, object colortable)
string encode_trans(object img, object alpha)
string encode_trans(object img, int tr_r, int tr_g, int tr_b)
string encode_trans(object img, int colors, object alpha)
string encode_trans(object img, int colors, int tr_r, int tr_g, int tr_b)
string encode_trans(object img, int colors, object alpha, int tr_r, int tr_g, int tr_b)
string encode_trans(object img, object colortable, object alpha)
string encode_trans(object img, object colortable, int tr_r, int tr_g, int tr_b)
string encode_trans(object img, object colortable, object alpha, int a_r, int a_g, int a_b)
string encode_trans(object img, object colortable, int transp_index)

Description

Create a complete GIF file.

The latter (encode_trans) functions add transparency capabilities.

Example:

img=<ref>Image.Image</ref>([...]);
[...] // make your very-nice image
write(<ref>Image.GIF.encode</ref>(img)); // write it as GIF on stdout

Parameter img

The image which to encode.

Parameter colors

Parameter colortable

These arguments decides what colors the image should be encoded with. If a number is given, a colortable with be created with (at most) that amount of colors. Default is '256' (GIF maximum amount of colors).

Parameter alpha

Alpha channel image (defining what is transparent); black color indicates transparency. GIF has only transparent or nontransparent (no real alpha channel). You can always dither a transparency channel: Image.Colortable(my_alpha, ({({0,0,0}),({255,255,255})}))
->full()
->floyd_steinberg()
->map(my_alpha)

Parameter tr_r

Parameter tr_g

Parameter tr_b

Use this (or the color closest to this) color as transparent pixels.

Parameter a_r

Parameter a_g

Parameter a_b

Encode transparent pixels (given by alpha channel image) to have this color. This option is for making GIFs for the decoders that doesn't support transparency.

Parameter transp_index

Use this color no in the colortable as transparent color.

Note

For advanced users:

Image.GIF.encode_trans(img,colortable,alpha);

is equivalent of using

Image.GIF.header_block(img->xsize(),img->ysize(),colortable)+
Image.GIF.render_block(img,colortable,0,0,0,alpha)+
Image.GIF.end_block();

and is actually implemented that way.