L_IntelligentDownScaleBitmap

#include "l_bitmap.h"

L_LTIMGSFX_API L_INT L_IntelligentDownScaleBitmap (pBitmap, pMaskBitmap, crRemoveObjectColor, crPreserveObjectColor, nNewWidth, nNewHeight, nDownScalingOrder, uFlags)

Reduces the image size while preserving important features automatically. Also, it can remove or preserve certain objects chosen by the user without affecting the natural look of the image.

This feature is available in version 16 or higher.

Returns

Comments

Sometimes dark areas are affected during downscaling since dark areas are considered to be  "unimportant". To prevent dark objects from being affected during downscaling, negate the image, apply downscaling, then negate the image again to get the colors of original image. Alternatively, apply a mask on the dark objects.

Intelligent downscaling has limitations when images are too condensed or where the content layout prevents the downscaling from being performed correctly without harming important parts.

Downscaling performed using a mask is done only on the width dimension. To downscale using a mask on the height dimension, rotate the image, downscale the width dimension, then rotate the image again.

The mask color for an area being removed must be different from the colors in the image. If multiple "remove" objects are masked, all must have the same mask color.

The mask color of the "preserve" area must be different than colors in the image, and different from the remove area color. If multiple "preserve" objects are masked, then all must have the same mask color.

To make the amount of downscaling equal to the size of remove area, set the new width equal to the image width. This does NOT apply to preserve area and does NOT apply to the intelligent upscaling.

Sometimes, setting the new dimension does not totally delete the remove area. In this case, pass a new width to the original image that is less than the width of the (failed) downscaled image. For instance, if the downscaled image width is 300 pixels, but still has a few lines remaining of the remove area after downscaling reset the width to 290 pixels and re-do the downscale.

If a mask has a preserve area but no remove area, you must specify nNewWidth.

For best results, draw the mask from top to bottom of the image, passing over the remove area. Make the mask wide enough to force downscaling to be performed only in the remove area.

This function does not support 12 or 16-bit grayscale or 48 or 64-bit color images. If the image is 12 or 16-bit grayscale or 48 or 64-bit color, the function will not return an error.

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

This function does not support 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

Required DLLs and Libraries

Platforms

Win32, x64.

#define MAKE_IMAGE_PATH(pFileName) TEXT("C:\\Users\\Public\\Documents\\LEADTOOLS Images\\")pFileName 
L_INT IntelligentDownScaleExample(L_VOID) 
{ 
   L_INT nRet; 
   BITMAPHANDLE LeadBitmap;   // Bitmap handle to hold the loaded image. 
   nRet=L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("SAMPLE3.CMP")), &LeadBitmap,sizeof(BITMAPHANDLE), 0, ORDER_RGB, NULL, NULL); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet=L_IntelligentDownScaleBitmap(&LeadBitmap, NULL, (COLORREF)INTELLIGENTRESCALE_NOREMOVECOLOR, (COLORREF)INTELLIGENTRESCALE_NOPRESERVECOLOR, 
   500, LeadBitmap.Height, INTELLIGENTRESCALE_VERTHORZ, 0); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL); 
   if(nRet !=SUCCESS) 
      return nRet; 
   L_FreeBitmap(&LeadBitmap); 
   return SUCCESS; 
}