How to create a bitmap with 8 bits (256 colors), not grayscale!

[JScript]

Hello friends!

I already know how to make 8-bit grayscale using _WinAPI_CreateDIBSection() function, but unfortunately I could not understand well and I do not know if it is possible to obtain the results posted on this link:
http://en.wikipedia.org/wiki/Color_depth # 8-bit_color

I appreciate any help,

JS

[UEZ]

Do you want to create an empty 8-bit bitmap or convert an image to 8-bit image?

1) Create an empty 8-bit bitmap -> _GDIPlus_BitmapCreateFromScan0() using $GDIP_PXF08INDEXED as the pixel format

2) Check out _GDIPlus_BitmapConvertFormat() function in the help file

Br,

UEZ

[JScript]

Hello, thanks for the reply, but do not actually need to convert, note the code below:

$iBitCount = 8

$hSrcDC = _WinAPI_GetDC(_WinAPI_GetDesktopWindow())
$hDestCDC = _WinAPI_CreateCompatibleDC(0)

$tBMPINFO = DllStructCreate("dword Size; long Width; long Height; word Planes; word BitCount; dword Compression; dword SizeImage; long XPelsPerMeter; long YPelsPerMeter; dword ClrUsed; dword ClrImportant; dword RGBQuad[256];")
DllStructSetData($tBMPINFO, "Size", 40);DllStructGetSize($tBITMAPINFO) - 4);
DllStructSetData($tBMPINFO, "Planes", 1)
DllStructSetData($tBMPINFO, 'Compression', 0);$BI_RGB)
DllStructSetData($tBMPINFO, 'SizeImage', 0)
DllStructSetData($tBMPINFO, "Width", $iWidth)
DllStructSetData($tBMPINFO, "Height", -($iHeight)); minus =standard = bottomup
DllStructSetData($tBMPINFO, "BitCount", $iBitCount)
If $iBitCount <= 8 Then
    $iColorCnt = BitShift(1, -$iBitCount)
    DllStructSetData($tBMPINFO, 'ClrUsed', $iColorCnt)
    DllStructSetData($tBMPINFO, 'ClrImportant', $iColorCnt)
EndIf
Switch $iBitCount
    Case 8
        For $i = 0 To $iColorCnt - 1
            DllStructSetData($tBMPINFO, 'RGBQuad', BitOR(BitShift($i, -16), BitShift($i, -8), $i), $i + 1)
        Next
    Case 4
        Local $aCol[16] = [8, 24, 38, 56, 72, 88, 104, 120, 136, 152, 168, 184, 210, 216, 232, 248]
        For $i = 0 To 15
            DllStructSetData($tBMPINFO, 'RGBQuad', BitOR(BitShift($aCol[$i], -16), BitShift($aCol[$i], -8), $aCol[$i]), $i + 1)
        Next
    Case 1
        DllStructSetData($tBMPINFO, 'RGBQuad', BitOR(BitShift(0xFF, -16), BitShift(0xFF, -8), 0xFF), 2)
EndSwitch

$hHBitmap = _WinAPI_CreateDIBSection($hDestCDC, $tBMPINFO, $DIB_RGB_COLORS, $pBits)
_WinAPI_SelectObject($hDC, $hHBitmap)

_WinAPI_StretchBlt($hDestCDC, $iWndX, $iWndY, $iWndW, $iWndH, $hSrcDC, $iXSrc, $iYSrc, $iWidthSrc, $iHeightSrc, $SRCCOPY)

In this way I can take a screen shot on 8 bits but unfortunately is in shades of gray!

 

How to get a colored with only 256 colors as shown in this link http://en.wikipedia.org/wiki/Color_depth?

 

Edit1:

Sample image of 8 bit (256 colors):

Edit2:

After playing a bit with the "bmiColors" I got this result:

But you may notice that the color white is "saturated", as well as the black color is also!

Edit3:

After some testing, the maximum I got was this result:

But I'm not sure that is correct because I'm Colorblind...

JS

Edited July 27, 2014 by JScript

[UEZ]

It looks good (edit 3 screenshot).

You need it for your RDP app, right? If yes, then GDI+ might be the wrong choice. GDI is faster.

Br,

UEZ

Edited July 27, 2014 by UEZ

[JScript]

It looks good (edit 3 screenshot).

You need it for your RDP app, right? If yes, then GDI+ might be the wrong choice. GDI is faster.

Br,

UEZ

Yes is for my remote desktop program! Interesting to know that the bitmap has the same size if it is in grayscale!

I use Bitmap cache that minimizes the amount of bitmap data transferred between the client and server. The client creates an compressed, temporary bitmap cache that contains bitmaps that are repeatedly sent from the server to the client.

The client uses GDI calls and these cached bitmaps to draw onto the display. The cache resides in RAM and is valid for the session.

When the code is complete I'll post for you to see,

Edit1:

Another variation. Better result?

Edit2:

See VNC with 256 colors to the left of the picture and my program in the right of the image:

JS

Edited July 27, 2014 by JScript

[UEZ]

Edit1 is dithered but I like more your Edit2 result.

Br,

UEZ

[JScript]

Edit1 is dithered but I like more your Edit2 result.

Br,

UEZ

Thank you friend!

Based on the explanations of these two links:

http://msdn.microsoft.com/en-us/library/bb250466%28VS.85%29.aspx#safety_topic2

https://www.gidforums.com/t-21296.html

I got the final conclusion, see:

Capture with 8bits and SetStretchBltMode in COLORONCOLOR:

Capture with 8bits and SetStretchBltMode in HALFTONE:

JS