解决颜色增强功能映射到过滤的问题

sane/scanned_img.cpp

@@ -469,6 +469,7 @@ std::string scanned_img::file_header(SANE_ImageType type, float resolution)
 			pal_size = 2 * sizeof(int);
 		else if (bih.biBitCount == 8)
 			pal_size = 256 * sizeof(int);
+		bih.biClrUsed = pal_size / sizeof(int);			// some APP (PJScanner.exe 光大……) use this field to calculate pallete
 
 		{
 			BITMAPFILEHEADER	fh = { 0 };

twain/twain/huagaods.cpp

@@ -3202,7 +3202,7 @@ void huagao_ds::init_support_caps(void)
 				if (Msg::Set == msg)
 					def = data.currentItem<UInt32>();
 				int ret = SCANNER_ERR_OK;
-				SET_SANE_OPT_EX(ret, scanner_, ex_color_filter, &def);
+				SET_SANE_OPT_EX(ret, scanner_, ex_color_enhance, &def);
 				return ret == SCANNER_ERR_OK ? success() : badValue();
 			}