Bad quality with GIF (and GDI+)

[Enrico Maria Giordano]

I'm using the new GDI+ function and they work very well with JPGs, TIFs and PNGs but GIFs are rendered with very bad quality.

Someone can confirm?

EMG

[Enrico Maria Giordano]

This is a sample. Please look at the very bad quality of the result. Any workaround?

Code: Select all  Expand view

#include "Fivewin.ch"


FUNCTION MAIN()

    LOCAL cSrcImage := "c:\fwh\bitmaps\magic.bmp"
    LOCAL cDstImage := "magic.gif"

    LOCAL oGdi := GDIBmp():New( cSrcImage )

    oGdi:Save( cDstImage )

    oGdi:End()

    RETURN NIL

EMG

[mastintin]

Enrico .
We had a picture of 32 or 24 bits to 8 bits . The maximum number of colors is 256 for gif files.
The problem is that Microsoft gdi+ also uses the halftone palette (compatible 100% web) for gif conversion,which it makes the colors that are not in the table web It is changed to the nearest.
There is no easy solution .
We would have to:
go to gdi1.0 to GDI 1.1 and some operating systems let out (not good).

It could save the original palette but not as we could tell GDI+ to use that instead the halftone palette when save image .

[Enrico Maria Giordano]

So, it would be honest to drop the GIF compatibility.

EMG

[Enrico Maria Giordano]

Or to find another way to load a GIF.

EMG

[Enrico Maria Giordano]

go to gdi1.0 to GDI 1.1 and some operating systems let out (not good).

What Windows versions support GDI+ 1.1 natively?

EMG

[mastintin]

go to gdi1.0 to GDI 1.1 and some operating systems let out (not good).

What Windows versions support GDI+ 1.1 natively?

EMG

Vista and more ...
and some borland compiler not support gdi+1.1

[mastintin]

more news...
https://msdn.microsoft.com/en-us/library/aa479306.aspx
here all code in C ++ to use ColorQuantizer.
http://www.codeguru.com/cpp/g-m/gdi/gdi ... ctrees.htm

[Enrico Maria Giordano]

more news...
https://msdn.microsoft.com/en-us/library/aa479306.aspx
I guess you can adapt the code. When you have a little time I look at you could do.

Do you mean *you* can adapt the code?

Thank you.

EMG

[mastintin]

here all code in C ++ to use ColorQuantizer.
http://www.codeguru.com/cpp/g-m/gdi/gdi ... ctrees.htm

[Enrico Maria Giordano]

Sorry, I cannot be of any help on this subject...

EMG

[Enrico Maria Giordano]

I just made a test: I replace GDIP_IMAGEFROMFILE() with FILOADIMG() and the result is how is should be. So the problem seems to be located in the loading function GDIP_IMAGEFROMFILE() (and probably in GDIPLUSIMAGELOADCACHEDFILE() too).

I don't know if this can help though.

EMG

[mastintin]

in c:\fwh\source\winapi\gdiplus.cpp

[mastintin]

Enrico , provisional solution .....
Change this Method in gdiplus class C:\fwh\source\clases\tgdiplus.prg

Code: Select all  Expand view

METHOD Save( cFile , nQuality ) CLASS GDIBmp
local cExtension := Upper(cFileExt(cFile))
local cCLSID
local hQuality := nil
local nScan:= aScan( ::aExtEnd, cExtension )
//local cGUI := AnsiToWide("{1D5BE4B5-FA4A-452D-9CDD-5DB35105E7EB}" )

local cTempFile

if nScan == 0
    msginfo( "Formato no soportado" )
    Return .f.
endif

if cExtension == "GIF"
   nScan := 1
endif

 cCLSID := ::aCLSID[ nScan ]

 cCLSID = AnsiToWide( cCLSID )
 cFile  = AnsiToWide( cFile )

if cExtension == "GIF"
    cTempFile := cTempFile()
   GdiPlusImageSave( ::hBmp, cTempFile, cCLSID )
   FIConvertImageFile( cTempFile, cFile )
   FErase( cTempFile )
 
else
   if !Empty( nQuality ) .and. cExtension == "JPG"
        GdiPlusImageSaveQuality( ::hBmp, cFile, cCLSID, nQuality )
   else
       GdiPlusImageSave( ::hBmp, cFile, cCLSID )
   endif
endif

Return nil

 

[Enrico Maria Giordano]

If I read correctly, it uses FreeImage, right? If yes, it's not a useful solution, sorry.

EMG