Newsgroup: it.comp.lang.visual-basic
Titolo: Conversione Bitmap

Ciao a tutti,
qualcuno sa come si fa a convertire una Bitmap (24,32 bit) in una a 2 Bit
(monocromatica bianco e nero)?????
Grazie
Fabio

 (monocromatica bianco e nero)?????
Con qualunque programma di fotoritocco..consiglio per quello che devi fare
Macromedia FreeHand...!!

 ha scritto nel messaggio
news:1zkX6.64244$Cq5.6...@news.infostrada.it...

Scusa ma forse non mi sono espresso bene:
intendevo via CODICE :)))
Grazie
Fabio


Newsgroups: vb.multimedia_graphics
Subject: Re: reducing colors to 256
Date: Mon, 3 Jan 2000 12:15:58 -0500
Bitmap files start with a fileheader, then an infoheader, followed by
the
palette entries (unless it's a 24-bit bmp), and finally the bitmap bits
themselves.  The only complication is that the palette and bitmap bits
are
Dword-aligned, which means that palette entries are RGBQUADs, and each
scan
line of bitmap bits has to have an even multiple of 4 bytes (up to 3
padding
bytes are added if necessary).
I've got a routine here to save a picturebox as a monochrome bitmap: you
should find it pretty easy to change it for 16- and 256-color standard
palettes (if not, just ask more questions here!).  Custom palettes are
quite
a bit more work...
Oh, and the picturebox must have AutoRedraw = True, ScaleMode = vbPixel
(3).
Good luck!
Jim Deutch
MS Dev MVP
Private Type BITMAPFILEHEADER    '14 bytes
   bfType As Integer
   bfSize As Long
   bfReserved1 As Integer
   bfReserved2 As Integer
   bfOffBits As Long
End Type
Private Type BITMAPINFOHEADER   '40 bytes
   biSize As Long
   biWidth As Long
   biHeight As Long
   biPlanes As Integer
   biBitCount As Integer
   biCompression As Long
   biSizeImage As Long
   biXPelsPerMeter As Long
   biYPelsPerMeter As Long
   biClrUsed As Long
   biClrImportant As Long
End Type
Private Type RGBQUAD
   rgbBlue As Byte
   rgbGreen As Byte
   rgbRed As Byte
   rgbReserved As Byte
End Type
Private Type BITMAPINFO_1
   bmiHeader As BITMAPINFOHEADER
   bmiColors(1) As RGBQUAD
End Type
Private Const PIXEL As Integer = 3
Private Const DIB_RGB_COLORS As Long = 0
Private Const PALVERSION = &H300
Private Declare Function GetDIBits1 Lib "gdi32" Alias "GetDIBits" _
  (ByVal aHDC As Long, ByVal hBitmap As Long, ByVal nStartScan As Long,
_
  ByVal nNumScans As Long, lpBits As Any, lpBI As BITMAPINFO_1, _
  ByVal wUsage As Long) As Long
Private Sub Save1(pic As PictureBox)
Dim SaveBitmapInfo_1 As BITMAPINFO_1
Dim SaveFileHeader As BITMAPFILEHEADER
Dim SaveBits() As Byte
Dim BufferSize As Long
Dim fNum As Long
Dim Retval As Long
Dim nLen As Long
Const BitsPixel = 1
    'size a buffer for the pixel data
    BufferSize = ((pic.ScaleWidth / 8 + 3) And &HFFFC) * pic.ScaleHeight
    ReDim SaveBits(0 To BufferSize - 1)
    'fill the header info for the save copy
    With SaveBitmapInfo_1.bmiHeader
        .biSize = 40
        .biWidth = pic.ScaleWidth
        .biHeight = pic.ScaleHeight
        .biPlanes = 1
        .biBitCount = BitsPixel
        .biCompression = 0
        .biClrUsed = 0
        .biClrImportant = 0
        .biSizeImage = BufferSize
    End With
    nLen = Len(SaveBitmapInfo_1)
    'get the bitmap from the picturebox
    Retval = GetDIBits1(pic.hdc, pic.Image, 0, _
        SaveBitmapInfo_1.bmiHeader.biHeight, SaveBits(0),
SaveBitmapInfo_1,
DIB_RGB_COLORS)
    ' create a header for the save file
    With SaveFileHeader
       .bfType = &H4D42
       .bfSize = Len(SaveFileHeader) + nLen + BufferSize
       .bfOffBits = Len(SaveFileHeader) + nLen
    End With
    ' save it to disk
    fNum = FreeFile
    Open m_SaveFileName For Binary As fNum
    Put fNum, , SaveFileHeader
    Put fNum, , SaveBitmapInfo_1
    Put fNum, , SaveBits()
    Close fNum
End Sub


Perfetto grazie!
Ciao
Fabio


----CUT----
Ciao
Scusa, io gli passo un file da 418KB e lui trasformandolo me ne crea uno a 2
BIT da 6565KB è normale? perchè usando un programma grafico tipo Paint di
WIN me ne crea uno di 14KB!!!!!
Grazie
Fabio

Azz la mia solita fretta......
Funziona tutto 8))))
Grazie e scusa ancora.....
Fabio

 intendevo via CODICE :)))
Scusa me se non ti ho capito! :-)))