Loading/Modifying Pallettes of 256 color bitmaps

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Socoder -> Blitz Max -> Loading/Modifying Pallettes of 256 color bitmaps
Sat, 25 Aug 2007, 21:54
Mog	Hello all. Does anyone know the format structure of a 256 color bitmap? I am trying to make a loader that can also modify the pallette on the fly within games (So you can make team colors easily) -=-=- I am Busy Mongoose - My Website Dev PC: AMD 8150-FX, 16gb Ram, GeForce GTX 680 2gb Current Project: Pyroxene
Sat, 25 Aug 2007, 21:56
HoboBen	Wotsit format usually has everything. This bit and this bit have some links. -=-=- blog \| work \| code \| more code
Sun, 26 Aug 2007, 00:08
Mog	Seems at the moment I have it working slightly well, though the drawing routine is a little fickle. Edit Here is my code. It's messy but I want to see if this will produce the same results that im getting. Graphics 800,600,0,0,2 Stream=OpenStream("output.bmp",True,False) Local colorR[256] Local colorG[256] Local colorB[256] '-Header- Print "===BITMAP HEADER===" Print "Byte 1:"+ReadShort(Stream) Print "File Size:"+ReadInt(Stream) Print "RESERVED:"+ReadShort(Stream) Print "RESERVED:"+ReadShort(Stream) Print "Data Offset:"+ReadInt(Stream) Print "Size:"+ReadInt(Stream) Width=ReadInt(Stream) Height=ReadInt(Stream) Print "Planes:"+ReadShort(Stream) Print "BitCount:"+ReadShort(Stream) Print "Compression:"+ReadInt(Stream) Print "Image Pad Size:"+ReadInt(Stream) Print "Pixel Scale Device X:"+ReadInt(Stream) Print "Pixel Scale Device Y:"+ReadInt(Stream) Cnum=ReadInt(Stream) Print CNum Print "Important Colors:"+ReadInt(Stream) '---------------------------------------------- Print "=============================" Print "Header is:"+StreamPos( Stream )+" Bytes" For i=0 To Cnum ColorB[i]=ReadByte(Stream) ColorG[i]=ReadByte(Stream) ColorR[i]=ReadByte(Stream) res=ReadByte(Stream) 'If i=50 'ColorB[i]=0 ''ColorG[i]=0 'ColorR[i]=0 'EndIf SetColor ColorR[I],ColorG[I],ColorB[I] DrawRect i*2,550,2,50 Next OutMsg$="Press a key to Continue Loading Image" SetColor 255,255,255 DrawText OutMsg$,(GraphicsWidth()-TextWidth(OutMsg$))/2,GraphicsHeight()/2 Flip WaitKey() Image=CreateImage(Width,Height) Map=LockImage(Image) Start=MilliSecs() While Not End_Parse index=ReadByte(Stream) Argb=255 Shl 24 + ColorR[Index] Shl 16 + ColorG[Index] Shl 8 + ColorB[Index] WritePixel(map,RowX,(Height-1)-RowY,argb) RowX:+1 If RowX>Width RowX=0 RowY:+1 EndIf If RowY=Height End_Parse=True EndIf Wend CloseStream Stream UnlockImage Image Print "Time To Create Pixmap:"+(MilliSecs()-Start)+"MS" While Not KeyDown(Key_escape) DrawImage Image,MouseX()-(ImageWidth(Image)/2),MouseY()-(ImageHeight(Image)/2) Flip Cls Wend --v -=-=- I am Busy Mongoose - My Website Dev PC: AMD 8150-FX, 16gb Ram, GeForce GTX 680 2gb Current Project: Pyroxene
Sun, 26 Aug 2007, 04:41
spinal	I did this recently to read a specific size and bit depth image, it should work fine if you read the palette size and image dimensions from the header. Graphics 320,240,0,2 Dim pal(255,2) bitmap=ReadFile("input.bmp") SeekFile(bitmap,54) ; offset for palette For t=0 To 255 pal(t,2)=ReadByte(bitmap) pal(t,1)=ReadByte(bitmap) pal(t,0)=ReadByte(bitmap) c1=ReadByte(bitmap) ; unused i think Next Cls For y=0 To 191 ; height For x=0 To 255 ; width pixel=ReadByte(bitmap) Color pal(pixel,0),pal(pixel,1),pal(pixel,2) Plot x+2,200-y Next Next CloseFile bitmap WaitKey() End --v I think the main thing to remember is that the palette has 4 entries per color, rather than 3. -=-=- Check out my excellent homepage!
Sun, 26 Aug 2007, 06:03
Teasy	If you only need to replace a few colors, you could apply a mask to a color on the loaded image drawn on top of a background of the new color. I have a function for this in Blitz2D/3D, but I think it's possible to convert it to BlitzMax. ; replace one color (from_color) with another (to_color) in an image (ori_img) with optional mask (mask_color) Function replace_color( ori_img , from_red,from_green,from_blue , to_red,to_green,to_blue , mask_red=0,mask_green=0,mask_blue=0 ) Local new_img ; create a new image with the same size as the original new_img = CreateImage( ImageWidth( ori_img ),ImageHeight( ori_img ) ) ; paint the new image background with the new color (to_color) SetBuffer ImageBuffer( new_img ) ClsColor to_red,to_green,to_blue Cls ; make the old color (from_color) 100% transparent (masked) MaskImage ori_img , from_red,from_green,from_blue ; then draw it over the background DrawImage ori_img , 0,0 ; finally set the original masking color (if used) MaskImage new_img , mask_red,mask_green,mask_blue ; reset color and free image ClsColor 0,0,0 FreeImage ori_img Return new_img End Function --v
Sun, 26 Aug 2007, 23:00
Mog	All of this works (The Loader at Least...) But one stupid detail is giving me a headache: I'm using really large bitmaps (ones like 4096x8192 .. so thats one of the reasons why i wanted a 256 color bitmap loader in the first place: Vmem conservation!) But it seems theres no quick way to draw them! Pixmaps are ungodly slow, and simply converting them to an image rebloats them to use 24 bit color! How did they do this back in the old days with games like Starcraft? I'm failing to make the connection... -=-=- I am Busy Mongoose - My Website Dev PC: AMD 8150-FX, 16gb Ram, GeForce GTX 680 2gb Current Project: Pyroxene
Mon, 27 Aug 2007, 08:02
mike_g	I have noticed that big bitmaps sometimes do weird things on different systems. Probably to do with the graphics cards. Since 4096x8192 is bigger than any screen anyways could you not perhaps split it into, say, eighths and tile it?
Mon, 27 Aug 2007, 23:45
Mog	It's not exactly a Bitmap -- It's a Pixmap that gets 'Windowed' into an image buffer. -=-=- I am Busy Mongoose - My Website Dev PC: AMD 8150-FX, 16gb Ram, GeForce GTX 680 2gb Current Project: Pyroxene