C语言编写简单图像程序-圆

最新推荐文章于 2024-08-28 07:00:06 发布

qianxuedegushi

最新推荐文章于 2024-08-28 07:00:06 发布

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分类专栏： C语言日志文章

本文链接：https://blog.youkuaiyun.com/qianxuedegushi/article/details/79047259

这篇博客介绍了如何使用C语言编写程序生成PPM图像格式，特别是绘制圆形。PPM是一种便携式像素图片格式，允许在不同平台间交换。文章详细解释了PPM文件的格式，包括ASCII和二进制两种表示方式，以及如何用C语言创建和保存PPM图像，包括设置像素和绘制圆的方法。

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生成图像格式：PPM

PPM图片格式介绍：

A Netpbm format is any graphics format used and defined by the Netpbm project. The portable pixmap format (PPM), the portable graymap format (PGM) and the portable bitmap format (PBM) are image file formats designed to be easily exchanged between platforms. They are also sometimes referred to collectively as the portable anymap format (PNM),^[4]^[5] not to be confused with the related portable arbitrary map format.

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History[edit]

The PBM format was invented by Jef Poskanzer in the 1980s as a format that allowed monochrome bitmaps to be transmitted within an email message as plain ASCII text, allowing it to survive any changes in text formatting.^[5] Poskanzer developed the first library of tools to handle the PBM format, Pbmplus, released in 1988. It mainly contained tools to convert between PBM and other graphics formats. By the end of 1988, Poskanzer had developed the PGM and PPM formats along with their associated tools and added them to Pbmplus. The final release of Pbmplus was December 10, 1991.

In 1993, the Netpbm library was developed to replace the unmaintained Pbmplus. It was simply a repackaging of Pbmplus with additions and fixes submitted by people all over the world.^[6]

File format description[edit]

Each file starts with a two-byte magic number (in ASCII) that identifies the type of file it is (PBM, PGM, and PPM) and its encoding (ASCII or binary). The magic number is a capital P followed by a single-digit number.

Type	Magic number		Extension	Colors
Type	ASCII	Binary	Extension	Colors
Portable BitMap^[1]	`P1`	`P4`	`.pbm`	0–1 (white & black)
Portable GrayMap^[2]	`P2`	`P5`	`.pgm`	0–255 (gray scale)
Portable PixMap^[3]	`P3`	`P6`	`.ppm`	0–255 (RGB)

A value of P7 refers to the PAM file format that is covered as well by the netpbm library.^[7]

The ASCII formats allow for human readability and easy transfer to other platforms; the binary formats are more efficient in file size but may have native byte-order issues.