L_HistoEqualizeBitmap (original) (raw)

Summary

Linearizes the number of pixels, in a bitmap, based on the specified color space. This function is also useful for pre-processing images for the purpose of improving barcode recognition results.

Syntax

#include "l_bitmap.h"

L_LTIMGCLR_API L_INT L_HistoEqualizeBitmap(pBitmap, uFlags)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to be changed.

L_UINT32 uFlags

Flag that indicates which color space to equalize. Possible values are:

Returns

Comments

To update a status bar or detect a user interrupt during execution of this function, refer to L_SetStatusCallback.

Previously this function only equalized the number of pixels per gray level, using a gray level representation of the image. This functionality is now obtained by passing GRAY_SPACE for uFlags.

For the best results, set uFlags to YUV_SPACE.

This function can process the whole image or a region of the image.

This function supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available in the Document and Medical Imaging toolkits.

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.

Histogram Equalize Function - Before

Histogram Equalize Function - After

View additional platform support for this Histogram Equalize function.

Required DLLs and Libraries

• LTIMGCLR
• For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64, Linux.

See Also

Functions

• L_ChangeBitmapIntensity
• L_GammaCorrectBitmap
• L_ChangeBitmapContrast
• L_HistoContrastBitmap
• L_StretchBitmapIntensity
• L_RemapBitmapIntensity
• L_InvertBitmap
• L_ChangeBitmapHue
• L_ChangeBitmapSaturation
• L_FillBitmap
• L_GetPixelColor
• L_PutPixelColor
• L_GetBitmapHistogram
• L_WindowLevel
• L_ChannelMix
• L_DeinterlaceBitmap
• L_DesaturateBitmap
• L_EdgeDetectStatisticalBitmap
• L_LightControlBitmap
• L_SmoothEdgesBitmap
• L_LocalHistoEqualizeBitmap
• L_AddWeightedBitmaps
• L_ColorMergeBitmap
• L_ColorSeparateBitmap
• L_ConvertColorSpace
• L_MultiplyBitmap
• L_AutoColorLevelBitmap
• L_ColorLevelBitmap
• L_CorrelationBitmap
• L_GrayScaleToDuotone
• L_GrayScaleToMultitone
• L_HolesRemovalBitmapRgn
• L_SelectiveColorBitmap
• L_SkeletonBitmap
• L_ChangeHueSatIntBitmap
• L_ColorReplaceBitmap
• L_ColorThresholdBitmap
• L_MathFunctionBitmap
• L_SegmentBitmap
• L_AdaptiveContrastBitmap
• L_ApplyMathLogicBitmap
• L_ColorIntensityBalance
• L_ColorizeGrayBitmap
• L_ContBrightIntBitmap
• L_DigitalSubtractBitmap
• L_DynamicBinaryBitmap
• L_EdgeDetectEffectBitmap
• L_FunctionalLightBitmap
• L_MultiScaleEnhancementBitmap
• L_SelectBitmapData
• L_ShiftBitmapData

Topics

• Raster Image Functions: Modifying Intensity Values
• Changing Brightness and Contrast
• Raster Image Functions: Changing Brightness and Contrast

Example

For complete sample code, refer to the CHILD.C module of the DEMO example.
This example loads a bitmap and applies histogram equalization.

L_INT HistoEqualizeBitmapExample(L_VOID) { L_INT nRet; BITMAPHANDLE LeadBitmap; /* Bitmap handle to hold the loaded image. */ /* Load the bitmap, keeping the bits per pixel of the file */ nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("IMAGE1.CMP")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); if (nRet != SUCCESS) return nRet; /* Histogram equalize the bitmap */ nRet = L_HistoEqualizeBitmap(&LeadBitmap, YUV_SPACE); 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; //free bitmap if (LeadBitmap.Flags.Allocated) L_FreeBitmap(&LeadBitmap); return SUCCESS; }

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