☆ Picture format
(I) bitmap
① also known as bitmap raster image, by pixel (picture element) of the single points. Usually divided into eight, 16-bit, 24-bit and 32-bit.
② so-called 8 Figure 8 are not the only colors, but the eighth power (256) 2 colors, 8 map refers to the use eight bits to represent the color, the feeling of the human eye, the 16 color to meet the basic needs.
③24 bit, also known as "true color", 24 th power of 2, there are about as many as 16 million colors, the figure is almost the limit of the human eye can distinguish the colors.
④32 32-bit color is not a power of 2, 24 in fact, is the power of 2, but it adds color gray Power Order 2 of 8 times, that is, eight of transparency, it is therefore specified 32-bit color.
⑤ in the production of the page, generally used in 24-bit image. Because 32-bit image will bring more image capacity will slow the browser to load the page.
⑥ enlargement of an original bitmap image is distorted, reducing the original bitmap, the same effect makes the image distortion, since reduced image, reducing the number of pixels in an image.
(Ii) bitmap format
①JPG format
Jpg image can deal well with large shades, such as photos, web pages general picture
②PNG format
PNG support transparent information. The so-called transparent, that image may emerge on the other page file or page image. When the image can be said that PNG is created specifically for the web, most usually added to the page designer logo or some little embellishment image in a page, would prefer to use PNG format. PNG format images of small size, and lossless compression, to ensure that web pages open faster, so the PNG image format is a good choice.
③GIF format
GIF supports only 256 colors within an image. So, GIF format images effect is poor. However, you can make animated GIF image using image processing software author, static GIF image is set to single frame, single frame and then put them together, set up a screen to the next interval of the screen, save for the final GIF format it. It can be said that this is a simple frame by frame animation.
When dealing with complex tones, brilliant images, such as photographs, drawings, etc., suitable for use jpg format; and deal with logo, banner, simple lines when the composition is suitable for use PNG format; GIF format are usually only suitable for expression animation.
(Iii) Vector
① vector format
Vector also known as "vector map." Vector dotted computer graphics, the image geometry based on mathematical equations represents in a straight line or polygonal.
Vector is a mathematical description of the way to record the image content of image formats. As an equation y = kx, when small equation reflected on a coordinate system, different parameters can be set at different angles draw a straight line, which is a vector diagram of the principle of the composition.
Vectors biggest advantages are: whether to zoom or rotation, the image will not be distorted. The biggest drawback is: difficult to demonstrate the rich colors vivid image effects.
② vector format
Vector suffix generally ".ai", ". Cdf", ". Swf" and ".fh".
".Ai" file with the extension file format is a vector of static frames. ".Cdf" suffix files are mostly drawings. ".Swf" file format refers to the Flash.
(Iv) difference bitmap and vector
① affected by the resolution of the bitmap, and vector graphics resolution is not affected. Accordingly, when the enlarged image, the bitmap resolution becomes low, and the sharpness vector unchanged.
② constituent units of the bitmap is "pixel", which consists of the unit vector is "mathematical vectors."
③ bitmap suitable for colorful images, and vector graphics do not apply to the colorful pictures.
④ commonly used in the page bitmap pictures, larger capacity; vector commonly used in the printing industry, page vector logo or illustration.