jpeg转换ppm
在线计算网 · 收录于 2022-08-08 11:41:04
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文件扩展名.jpeg
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文件类别images
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程序Adobe PhotoshopApple PreviewCorel Paint Shop Pro
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主程序MS Paint
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说明JPEG – is a popular graphic format, which is characterized by a high degree of compression, which leads to a decrease in image quality. It uses the technology of encoding of smooth color renditions, providing the ability to reduce the amount of data frequently during the recording of the image.
Because of the small size it is requested by the owners of websites, allowing you to save the traffic effectively. It is also frequently used in memory cards of digital video cameras. The JPEG algorithm is optimally suitable for compressing photographs and pictures, in which realistic scenes with little contrast of colors are present. It is not recommended to use this format for compression of drawings and various kinds of graphics, since a strong contrast between a number of closely located pixels provokes the appearance of visible artifacts.
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技术细节The procedure for compressing the digital images in JPEG format is carried out in several stages. First, the photo is transformed into a color space YCbCr, then it is divided into squares to determine the upper range of the color spectrum. Finally, the colors and brightness are coded.
JPEG uses a "lossy" compression system and discrete cosine transform technology. The format acts simultaneously as the standard of ISO and the International Telecommunication Union. The file compression ratio is in the range from 10:1 to 100:1. In this case, the reduction in image quality can vary from insignificant to substantial.
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MIME类型image/jpeg
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文件扩展名.ppm
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文件类别images
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程序Adobe PhotoshopCorel DrawGIMPNetpbm
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说明便携式的pixmap图像可以使用PPM格式是基本例如颜色（PPM），灰度（PGM）和黑和白（PBM）被存储。便携式的pixmap可以提供在被不同的平台之间提到的三种类型的位图图象文件的转换处理的信息的走廊表示。在PPM格式的发展是由Jeff Poskanzerom。
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技术细节PPM文件包括单个或多个PPM图像的序列。数据，填充和限制不之前或之后，或在图像的中间存在。每个PPM包括在文件的类型的识别中使用的单个幻数的;对于PPM图像的幻数是两个字符P6，空白（空格，制表符，CRS和LFS），并表示为十进制ASCII字符的宽度。它也包括一个空白的再一个高度，其在ASCII十进制呈现，一个空格，以最大（MAXVAL），其是用十进制形式并且它应该是大于零但小于65535，也由的颜色值另一单个空格字符，其大部分时间是在另一条线。最后，它是由它在相反的时间顺序发现高度的行的栅格的。这些行被在左到右格式由宽度像素。表示的样品具有纯二进制性质它是由一个或两个字节。余字节具有小于256，否则一MAXVAL，它是2个字节。第一个字节是最相关的。平原格式是PPM的另一个版本存在，但主要是少见。
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MIME类型image/x-ppmimage/x?portable?pixmap
