JPEG 추출 DCT 테이블

Question

VS2008, MFC 및 WIC를 사용하여 이미지 뷰어 / 편집기를 개발하고 있으며 이미지 처리 후 가능한 한 자세히 JPEG를 가능한 한 밀접하게 (Wize)을 다시 제거하고자합니다.누구든지 밝기와 색차 테이블을 추출하는 방법을 알고 있습니까? http://msdn.microsoft.com/ko.- 수 / 도서관 / GG430026 % 28v= vs.85 % 29.aspx (libjpeg와 같은 추가 대형 라이브러리)를 사용해야하는 ?

Answer 1

The JPEG standard specification covers the details of the luminance and chrominance table.

In JPEG terminology, those tables are both referred to as "quantization table" (DQT). The luminance quantization table is applied on the "Y" channel and the chrominance quantization table is applied to "Cb" and "Cr" channels.

This website lists the quantization tables for a large number of camera manufacturers and JPEG authoring software.

To recompress an image using the same quantization tables as another existing image:

• Query and enumerate all IWICMetadataBlockReader objects from the source image (IWICBitmapFrameDecode).
• Find the metadata blocks which have the types GUID_MetadataFormatJpegChrominance and GUID_MetadataFormatJpegLuminance
• Extract their binary data, and use those data to initialize the Luminance and Chrominance properties of the JPEG encoder options by putting them into the IPropertyBag when calling IWICBitmapFrameEncode::Initialize.