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 Posted: Sun 3:10, 08 May 2011 Post subject: mulberry outlet JPEG compression standard based on |
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JPEG compression standard based on the image format conversion, packaging and decorating
Standards for light gray and quantization tables, making the non-adaptive quantizer quantizer, as described on more and more detailed image features, such quantization table can not adapt,[link widoczny dla zalogowanych], so the DCT transform and quantization for the design to make improvements, Improved core content for the use of DCT DCT lookup table instead of a regular expression, which would ~ result of some fixed multiplication and division on the table, each time when the need to use a direct query from the operator; vector quantization in the quantization process instead of using the scalar quantified to 8 × 8 data blocks as a vector to quantify, so reducing the time to quantify and address the problem of redundancy between pixels. 3 3.1 Digital Image Compression of development tools is the subject of the development platform ViSUalC + +6.0, which is Microsoft's a very powerful visual application development tool. With traditional structured programming methods, object-oriented programming side enamel, research and development time is short, the development of high efficiency, the quality of generated code is better than other development tools. Therefore, the development of Win32 applications, VisualC + +6. O is the acknowledged excellent computer application development tools. 3.2RAW image display method 3.2.1RAW raw image display method in accordance with RBI each row and each column to store. A pixel can represent a byte (gray), can also account for 3 bytes (color). If the width is defined as the raw format image width, height image height for the raw format, then display a RAW format images of the algorithm can be shown by dot line, and its drawback is relatively slow rate of image display. 3.2.2 Using CDib class displays raw format is a plain image, this image format is no file header, then we can also add files to it first, to make it consistent with a BMP format, then use the image CDib class operation. 3.3JPEG JPG file image shows the whole implementation can be divided into two parts: the tag code (tag), the compressed data. Tag code section presents all the information JPG image, (somewhat similar to the BMP of the header information, but much more complex), such as image width, height, Huffman tables, quantization tables and so on. Code commonly used tags are: SOI, APPO, DQT, DRI, SOF, DHT, SOS, EOI. The display process shown in Figure 2. 3.4 Format conversion process implementation process of China Packaging 26o8/5-4 experimental results and analysis of digital image compression system in order to get the compression ratio, the size of a RAW image 64kB of multiple compression. Experiment, in accordance with the requirements of the user to set a different attribute value n-quality compression, and record the compressed JPEG image size and image. The following list only part of the experimental results,[link widoczny dla zalogowanych], and part of the original RAW image compression results compared visual effects (as shown in Table l). China Packaging 2008 / 5,[link widoczny dla zalogowanych], Table l part of the compression test results comparing visual effects can be seen from Table 1, n-quality higher property values, the compressed file size. Therefore, when the n-quality property value of 0, can clearly see the image quality deterioration of the property value when nquality 25, can see changes in image quality. From the experimental results can be seen in the premise of image quality, the digital image compression system can achieve a compression ratio of 70:1 or more. Of course, not every image compression on the compression ratio are the same, by the compression of other experimental analysis of RAW images can be drawn, compressed RAW image itself than even went to the size, quality and type and other factors. 5 Conclusion developed using VC + +6.0 software implementation of digital image compression RAW to JPEG conversion, the software has a small storage space, compression ratio, compression speed and other characteristics, but also in accordance with the requirements of users of digital images compression. From the experimental results, the compressed image quality in addition to the original image quality related, but also the compression ratio and image related, in general, the compression ratio on image quality compared hour will be much affected,[link widoczny dla zalogowanych], but more than a certain multiple of , will see the image quality decreased significantly, so in compression, in order to ensure image quality, the compression before the need to select the appropriate compression ratio. Image There are many types of formats, to name just two of the cases. In the analysis of the two format, other formats for image display,[link widoczny dla zalogowanych], just under the image storage structure, modify a small amount of code. Image analysis and image display format for the realization of a good foundation for further image processing, which plays an important role.
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