Bitmap images

[Dragoneyes718]

Does anybody know of a program that can convert to .raw, or if there is an editor that will allow you to save a bitmap as .raw?

[dmantione]

Netpbm is your friend: http://netpbm.sourceforge.net/

[Dragoneyes718]

Thats alot of stuff to sort through. I'm not entirely wure which to use. I am wanting .raw format because of the compatibility with PutImage in TP7.

[jdarling]

http://www.irfanview.com/

Best app I've found for this type of thing. Also works in batch mode, and is free. Now if you have money, then buy PSCS2 (PhotoShop CS2), its actually the best, but only a few of us developer geeks want to drop the cash on it :).

[Dragoneyes718]

Thanks! Now if someone could help me get the syntax right for using BlockRead in conjunction with .raw files for use with Putimage.

Anybocy know how to do this?

[dmantione]

Which graphics mode do you use?

[Dragoneyes718]

VGA 640x480
16 color

[dmantione]

For 16 colour modes you need to use 16 bpp packed pixel format. So, convert you image to such a format. Then, getmem a buffer with 6 bytes plus the size of the raw image. Then:

* At offset 0, write a word containing the width.
* At offset 2, write a word containing the height

Then blockread the image at offset 6. Now you should be able to use putimage.

[Dragoneyes718]

How should I define the buffer?

[dmantione]

I think an untyped pointer is the best solution. A pointer to a byte can also be usefull.

[Dragoneyes718]

Ok, and can Netpbm convert .bmp to what I need? If so, I'm having trouble getting that whole mess running... Sorry for all the questions, but I'm not very experienced with file formats etc.

Edit: And also, what is the correct syntax for writing, and reading at Offset?

[dmantione]

Not directly, because it cannot pack pixels in 4 bit nibbles. The easiest way is to read the ppm file, use bmptoppm to convert the bmp to a ppm file (which is basically a raw RGB file), read the ppm in memory and convert the individual pixels to nibbles.

To read at a specific offset you must construct a pointer to it, i.e.:


var p,q:Pbyte;

begin
getmem(p,1006); {Allocate buffer.}
q:=p;
inc(ptrrec(q).ofs,6); {q:=p+6 bytes}
blockread(f,q^,1000);
end;

[Dragoneyes718]

Ok, I've got everything, except how do you convert the pixels to nibbles?

[dmantione]

The raw RGB data is an array of rgb pixels. Each pixel is 3 bytes, first byte red, second byte green, third byte blue. Assuming the BMP picture was already 16 colours (otherwise you can reduce the amount of colours with with pnmremap), there are only 16 possibilities.

These are the 16 values of the CGA colour palette, see:

http://en.wikipedia.org/wiki/Color_Graphics_Adapter#The_CGA_color_palette

So, determine which colour you have, and the colour number is the pixel value.

Now you need to convert the colours to nibbles:

You have 16 colours, numbered from 0 to 15. So two pixels fit in one byte. The byte is calculated by:


var b:byte;

begin
b:=16*left_pixel + right_pixel;

[Dragoneyes718]

Thank you for all your help. But it's looking like I don't have all the resources to do most of this work. So... until I do, I hope I can get 1 more answer from you.
The other method I've been trying to use for this type of thing is saving GetImage data. I have made an editing program that lets me draw pixel by pixel whatever I want. Then, it lets me get the image size that I want and (maybe) saves the GetImage Data to a file. I have been able to load the data back and use it with PutImage later, but only if:
1. I haven't restarted the computer
2. It is the most recently saved file (by my program).
The problem I think is the way I'm trying to save it. I think I may be only saving the pointer variable to the file and it is still able to access the buffer for a while. I also am getting a garbled image if I try to access older image files.

So my question is, what is the CORRECT way to save the data?
Thanks in advance and for everything else. :)

[dmantione]

Something like this:

var buffer:Pbyte;
size:word;

begin
size:=imagesize(x1,y1,x2,y2);
getmem(buffer,size);
getimage(x1,y1,x2,y2,buffer^);
blockwrite(f,buffer^,size);
freemem(buffer,imagesize(x1,y1,x2,y2));

[Dragoneyes718]

Oh, ok, I was declaring buffer as a pointer. Could that be what messed it all up?

[dmantione]

That should be okay. You didn' t forget to getmem it?

[Dragoneyes718]

No, but maybe I'm having trouble because of the way I'm reading the file. What is the correct syntax to read it in, and then PutImage?

[dmantione]

Something like this:

var buffer:pointer;
size:word;

begin
size:=imagesize(x1,y1,x2,y2);
getmem(buffer,size);
blockread(f,buffer^,size);
putimage(x,y,buffer^);
freemem(buffer,size);

[Dragoneyes718]

I just get a disk read error. :?

[Dragoneyes718]

nevermind i figured it out!!!
Thank you very much for the help! :P