struct Screen *AppScreen = IIntuition->LockPubScreen(NULL);

// To allocate your bitmap:
struct Image myImage* = BitMapObject, BITMAP_SourceFile,
                        (STRPTR)"copy",
                        BITMAP_Screen, AppScreen,
                        BITMAP_Precision, PRECISION_EXACT,
                        BITMAP_Masking,TRUE, End;

// You must also dispose the bitmap once done with it.

IIntuition->DisposeObject(myImage);
IIntuition->UnlockPubScreen(NULL,AppScreen);

char buffer[512];

IUtility->Strlcpy(buffer,"progdir:",512);
IDOS->AddPart(buffer,myimagename,512);
myImage = LoadImage((STRPTR)buffer, AppScreen);
if (!myImage) // could not find images in progdir:
{
 IUtility->Strlcpy(buffer,"progdir:images/",512);
 IDOS->AddPart(buffer,myimagename,512);
 myImage = LoadImage((STRPTR)buffer, AppScreen);
}

if (!myImage) // could not find images in progdir:images
{
 IUtility->Strlcpy(buffer,"TBImages:",512);
 IDOS->AddPart(buffer,myimagename,512);
 myImage = LoadImage((STRPTR)buffer, AppScreen);
}

if (!myImage)
{
 // Could not find image file!
 // .. handle the error ..
}

// Where LoadImage() is:

struct Image *LoadImage(STRPTR buffer, struct Screen *AppScreen)
{
 return BitMapObject,
        BITMAP_SourceFile, buffer,
        BITMAP_Screen, AppScreen,
        BITMAP_Precision, PRECISION_EXACT,
        BITMAP_Masking,TRUE,
        End;
}