BMP to GIF Conversion

Hi Experts

i'm facing a problem in converting an image from BMP to GIF or JPG. i've an active x control which does the same thing. but i do not want to use any controls in my software.

my .exe should run without any dependencies.

can anybody give me some info. about how can i write an algo. to convert BMP to GIF. that should preferably in VB.

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iboutchkineConnect With a Mentor Commented:
Convert BMP to JPG with this code. (Note: Requires vic32.dll available from


Declare Function bmpinfo Lib "VIC32.DLL" (ByVal Fname As String, bdat As BITMAPINFOHEADER) As Long
Declare Function allocimage Lib "VIC32.DLL" (image As imgdes, ByVal wid As Long, ByVal leng As Long, ByVal BPPixel As Long) As Long
Declare Function loadbmp Lib "VIC32.DLL" (ByVal Fname As String, desimg As imgdes) As Long
Declare Sub freeimage Lib "VIC32.DLL" (image As imgdes)
Declare Function convert1bitto8bit Lib "VIC32.DLL" (srcimg As imgdes, desimg As imgdes) As Long
Declare Sub copyimgdes Lib "VIC32.DLL" (srcimg As imgdes, desimg As imgdes)
Declare Function savejpg Lib "VIC32.DLL" (ByVal Fname As String, srcimg As imgdes, ByVal quality As Long) As Long

' Image descriptor
Type imgdes
   ibuff As Long
   stx As Long
   sty As Long
   endx As Long
   endy As Long
   buffwidth As Long
   palette As Long
   colors As Long
   imgtype As Long
   bmh As Long
   hBitmap As Long
End Type

    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 Sub ConvertToJPEG(bmp_fname As String, jpg_fname As String, Optional quality As Long)
   Dim tmpimage As imgdes    ' Image descriptors
   Dim tmp2image As imgdes
   Dim rcode As Long
   'Dim quality As Long
   Dim vbitcount As Long
   Dim bdat As BITMAPINFOHEADER ' Reserve space for BMP struct
   'Dim bmp_fname As String
   'Dim jpg_fname As String

   'bmp_fname = "test.bmp"
   'jpg_fname = "test.jpg"

   If quality = 0 Then quality = 75
   ' Get info on the file we're to load
   rcode = bmpinfo(bmp_fname, bdat)
   If (rcode <> NO_ERROR) Then
      msgbox "error: Unable to get file info"
      Exit Sub
   End If
   vbitcount = bdat.biBitCount
   If (vbitcount >= 16) Then  ' 16-, 24-, or 32-bit image is loaded into 24-bit buffer
      vbitcount = 24
   End If
   ' Allocate space for an image
   rcode = allocimage(tmpimage, bdat.biWidth, bdat.biHeight, vbitcount)
   If (rcode <> NO_ERROR) Then
     msgbox "error: Not enough memory"
     Exit Sub
   End If
   ' Load image
   rcode = loadbmp(bmp_fname, tmpimage)
   If (rcode <> NO_ERROR) Then
      freeimage tmpimage ' Free image on error
      msgbox "error: Cannot load file"
      Exit Sub
   End If

   If (vbitcount = 1) Then ' If we loaded a 1-bit image, convert to 8-bit grayscale
       ' because jpeg only supports 8-bit grayscale or 24-bit color images
     rcode = allocimage(tmp2image, bdat.biWidth, bdat.biHeight, 8)
     If (rcode = NO_ERROR) Then
         rcode = convert1bitto8bit(tmpimage, tmp2image)
         freeimage tmpimage  ' Replace 1-bit image with grayscale image
         copyimgdes tmp2image, tmpimage
     End If
   End If

   ' Save image
   rcode = savejpg(jpg_fname, tmpimage, quality)
   freeimage tmpimage
   Kill bmp_fname
   msgbox "picture saved: " & jpg_fname
End Sub
I'm not sure whether this is any use, someone gave it to me the other day.  It changes a jpg to bmp, but you might be able to change it to the other way around.

Sub JPGtoBMP ()
LoadPic = LoadPicture(App.Path & "background.jpg")
SavePic = LoadPic
SavePicture SavePic.Picture, App.Path & "background.bmp"
End Sub

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DreamMaster - h_rangoonwala says he doesn't want to run with any dependencies. That link, although useful is an OCX, unfortunately.

I have seen proper VB code for saving from VB to GIF but it's rather complicated - I'll see if I can track it down. Most people in the situation usually resort to a third party DLL or EXE for this task.
Oops...I missed that line....

I'm sorry...thanks for pointing that out nutwiss....

I'll see if I can find "proper" VB code as well....


GIF is a proprietary format, you will need to pay a lisence fee if you want to have your own code doing the conversion. I think the company that owns it is called unisys, but I don't remember.

yes it is - ignore unisys... everyone else does... and anyway the patent expires in september 2003...
h_rangoonwalaAuthor Commented:
Thank u very much.

it helped me a lot

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