The kind of the picture file and How to use

There is something to which it very takes time to display the image when the homepage is inspected. Moreover, there is the one with dirty graph and illustration, too. When the usage of the image is bad, it might have unpleasant time. It thought about the kind and the usage of the picture file.

This page is a way that I recommend, and no one forced on others. It is needless to say to may your use of what image.

Kind of picture file

In the extension of the compressed image used on the Internet, three kinds (GIF, PNG, and JPG (Or, JPEG)) are the main. The PNG form is a form that looks like the GIF form well.

Moreover, there is a file of BMP (bit map) form not compressed either in the picture file.

Feature of picture file

Next, it characterizes it with the kind of the picture file. The patent cut in June, 2004 though the GIF file made excluding software with the license was not able to be opened to the public about patent (Unisys Co. in the United States) problem of the compressed algorithm.

Kind Deterioration
Feature of picture file
GIF Not deteriorated
  • If it is a simple image, the size of the file is smaller than the image of other forms.
  • The transfer imaging is possible. (It seems that the image is transparent.)
  • Interlace is possible. (Display it to a rough, at the beginning gradually detailed part when displaying it.)
  • The animation picture is possible. (easy animation)
  • Because only the color of 256 colors 8bit can be treated, it is suitable for the image that the number of colors is few and simple.
  • The number of colors is few inferior to that of power of expression, and the size of the file grows in the photograph though it is suitable for the illustration, too.
PNG Not deteriorated
  • The color that can be treated can be done from GIF and a lot of variegated expressions be done.
  • Interlace is more beautiful than GIF.
  • The size of the file is larger than that of GIF.
JPG Deteriorated
  • The number of colors is not suitable for the illustration though a lot of expressions are variegated suitable for the photograph of it.
  • There is not comparatively .that. so much deterioration in the image even if the size of the file is reduced by compressing it in the photograph.
  • When the compressibility is raised too much, the image is greatly deteriorated.
  • Whenever editing it, the image is deteriorated.
BMP Not deteriorated
  • The size of the file grows more than any the above-mentioned though there is no problem in the expression because it doesn't compress it.

Let's understand the kind and the feature of the picture file and use it well.

If the kind and the feature of the picture file are understood, this can be used properly well. I am making the schematic diagram, the calculating formula, the graph, the map, and the illustration GIF form. The image is not deteriorated at all no matter how it edits it. The size of the file can be reduced. I think that being possible to make it from the paint that has adhered to Windows free of charge easily is also good.

The photograph is often made JPG(JPEG) form, and when the character is put again in the photograph many times, it is likely to make it to PNG or the GIF form. The photograph of the JPG form doesn't edit it many times. It always copies from a former image and it edits it if it edits it.

Size of picture file (pixel) and size of file

The image used in general on the Internet should be made a moderate size (number of pixels on length and side) and moderate sizes of the file. When the number of pixels on length and side is too small, it becomes hard to see on the screen. It begins to be thought largeness from the screen and is necessary to scroll.

Moreover, when the size of the file is too large, it takes time to a user not broadband dial-up etc. for the display.

Generally, there might not be problem if length in the photograph and the number of pixels on side are adjusted to 200-400. This is a pixel count of the file, and no number of pixels (pixel count) on displayed length and side. The size on the disk of the file is adjusted to 50 kilobytes or less though 20 kilobytes or less are ideals.

I am uniting it to about 240X320 pixel in the photograph. It reduces with software "Reduction exclusive use". I think the size of the file for a lot of 30-40 kilobytes to exist.

Neither width nor the height attribute of the picture file are specified.

Pros and cons seem to be in width of the img file and a specified problem of the height attribute. I also had thought that specifying it by consideration to an old browser like Netscape Navigator 4 was indispensable up to now. However, I changed to no specification. Width of the img file and the specification of the height attribute are originally arbitrary in XHTML1.0 and HTML4.01. In a word, it is acceptable even if it doesn't specify it.

Advantage in which width and height are not specified

Because it is not necessary to describe it because neither width nor the height attribute are specified, time can be saved. Moreover, it becomes small though the size of the file is also a little.

A bigger advantage is that the correction of the HTML file becomes unnecessary in ..departure.. [toki] at another one and the image replacement. When it trims by editing the image and the number of pixels for the image changes even a little, it is necessary to correct not only the replacement of the picture file but also the HTML file. Otherwise, the image is transformed.

Neither width nor the height attribute are automatically input in Expression Web3 that began to be used recently though width and the height attribute are automatically input in the homepage builder. It is thought that this might become a standard in the future.

Disadvantage in which width and height are not specified?

The display area is secured before the image is read when width and height are specified for the img element. It was said that the display was slow because the display area was secured when the image was read when not specifying it. However, it seems not to be able to say indescribably because there is information that not specifying it was fast to display, too.