Discover how to create a shiny military themed ration package. This Adobe Illustrator tutorial is ideal for advanced users. We’ll use an interesting combination of techniques to create this themed package design. Let’s get started! Read the rest of this entry »
How to Create Your Own Stylized, Vector Badge
In this tutorial, we will learn how to illustrate a face with the help of a photo, and how to create a customized pin button out of it. This is a fun tutorial using relatively simple techniques. Let’s get to it! Read the rest of this entry »
Alpha Channels
Alpha Channels (Alpha Channels) can be used to correct very, browse. to create meshes (marquees). Especially in conjunction with smooth transitions between transparent and robust use alpha channels, but what is it really? Read the rest of this entry »
File Formats
File Formats
Adobe Photoshop has a variety of formats, which you can choose to hide in. It may seem confusing and unmanageable, but actually it is not so bad … Your camera also has probably the highest 3 different formats.
There are many ways to save their photos / drawings on. What format should be in store depends entirely on the medium as the image is presented.
Is it the Internet, desktop background or print / pressure? If it is print / prints are JPG since so bad?
I will review the most common and well-known graphic formats, complete with a brief description of their advantages and disadvantages, and provide examples of how it can be used.
BMP – Bitmap
BMP files are images stored in a raw bitmap format (not to be confused with camera RAW format). Other formats of the same type with the same qualities Examples include IMG, PCX, and DIB. These can contain almost infinite number of colors, but the disadvantage is that the format is a kind of RAW format, and therefore turns terribly much. Palette using the RGB (Red, Green, Blue). An image of 800×600 pixels will fill 1,440,000 bytes (equivalent to 1.37 megabytes), which we calculate 800 * 600 * 3! This format is largely used today by Microsoft, where they distribute their Windows, Office, etc. ..
This format is NOT web-friendly in that it fills very much compared to GIF, PNG and JPEG! However, it may well be used by all browsers can display BMP.
GIF – Graphics Interchange Format
GIF files are images stored in the max. 8-bit color, ie. 256 colors. This makes the course to a given image in GIF fills much smaller than an image, For example. 24 bit (16.7 million colors) stored in the aforementioned BMP. That unfortunately also means that there is cheerless much color information is lost.
On the other hand, GIF is one of only two formats that can store a picture with TRANSPARENT background – even when it appears in a web browser! Images are aware always square, and it can quickly look bad next to a picture with the yellow background on a website with black background. If you want to build a fancy title with transparent background, so you will typically choose GIF.
In addition, the GIF can be animated! You can save multiple images in a GIF file, and thus make a little short animation. Today, Flash, However, virtually taken over this function and GIF animations are used almost exclusively in the small icons to draw attention to itself (attention) in web …
GIF is suitable for Internet use, since it is supported by all browsers.
JPEG – Joint Photographic Experts Group
JPG / JPEG files are images stored in a compressed format destructive. This format can store the full 24 bit color, but by extreme hard compression is also very similar image, information is lost. It loses sharpness, detail and color the more you compress. The advantage is that JPEG can be compressed with an optional value! If you have a very colorful, nuanced and detail-rich image selected typically a low compression factor and has a mono-empty and simple image (a few colors, get crisp types) selected typically a HIGH compression factor. Even with a low compression factor will fill the image much smaller than a BMP!
JPEG is ideal for Internet use, since it is supported by ALL browsers in addition to space savings in the other end also makes it quick to show. On the other hand, it is more doubtful format to use for professional printing. You may as well save the 150 PPI intern (and for that matter, PPI dpi internal) and it actually makes that one may well use it for printing / processing in Photo instance Japan, Føtex or Bilka. In Photoshop you can save in JPEG in two ways, either as “save as” (quality: 1 – 12 WHERE 12 is the highest quality) Or “Save for Web ‘(quality: 1% – 100% where 100% is highest quality). Even at the very highest quality (100% in “Save for Web” Or 12 “save as”) the picture will lose a bit of information, and if you save the same image over itself, many times, it will slowly become worse and worse. It helps in other words, not to save a JPEG image at 100% quality; this will only spoil the picture further.
PSD – Adobe Photoshop
PSD files are images saved in Adobe Photo Shop image. They fill very much, because they are uncompressed. The advantage of the format is that it stores things such as layers, masks, and other miscellaneous settings adjustments. If you have edited / created an image from scratch in Photoshop, you should ALWAYS make sure to keep the PSD file with all layers intact, before compressing, For example. JPG or PNG. Furthermore, you can choose between several favorites’ (LIKE. RGB, sRGB, indexed and CMYK).
PSD is suitable for print / PRINT, but no pigeons around the internet, as it does not appear in browsers. Due Forma’s size, it is not suitable for the transport / forwarding.
PSP – Paint Shop Professional
PSP files have images saved in the Jasc Paint Shop Pro format. The formats are a response to Adobe Photo Shop and have similar properties.
PCD – Kodak PhotoCD
PCD files are images stored in Kodak format Photo CDs. It is available in 5 And 6 amateur professional formats. It can compress the non-destructive, which on the one hand, there will no loss of quality, while on the other hand means that you can still up in the relatively large size compared with JPG and PNG.
PNG – Portable Network Graphics
PNG is the “new” file format (from 1995), which is designed to replace JPEG and to some extent with GIF. It compresses the non-destructive (ie not as a JPEG), and can use transparency in more than 256 colors, ie. with true alpha channel (32 bit)! Especially the latter makes it a truly attractive format. It turns around half of a TIFF image, and quality is the same for the eye!
The reason why PNG has not been used fully yet, is probably that the format is not fully supported by Internet Explorer 6 (only version 7 can display 32-bit PNG correctly) and the slightly larger file size compared to JPG. PNG, However, in many respects the best format to use, especially if quality means more than the file size. PNG may apply different bit types; 1 bit per channel, 2 bits per channel, 4 bits per channel, 8 bits per channel and 16 bits per channel.
The loss-free compression as PNG uses a non-patented, and this has to do with the creation of PNG – which originally had a secondary role, namely “PNG – Not GIF”, by Unisys patented LZW algorithm (used, inter alia, in GIF format).
TIFF – Tagged Image File Format
TIFF files are images stored with the aim that they be used for press / PRINT. It is a professional format that compresses without information loss at all! This is done with LZW compression, which can be said to remind some of ZIP format can compresses anything. TIFF format is standard in the electronic graphics industry when you send files to hidden.
The format can not be used for internet, since it is not supported by browsers.
This was so little about the different file formats. As something else include Corel draws format. This use is not to point (pixel) Description, but by vectors. This implies that one can zoom infinitely without getting the familiar quality loss in the form of mouse stairs, color pixels, etc. It should then be said that the format be used only for computer drawings and example Can not take pictures, nor scan with it.
Here at last is a list of names of the different file formats:
AG4 Access G4 Document Imaging
TO AT & T Group IV
BMP Windows & OS / 2
BRK Brook Trout Fax
CAL CALS Group IV
CIT Intergraph Scanned Images
CLP Windows Clipboard
CMP Photo Matrix G3/G4 scanner format AND LEAD Technologies
CPR Knowledge Access
CT Scitex Continuous Tone
CUT Dr Halo
DBX DATABEAM
DCM DICOM medical image
Intel dcx fax
DX Auto Trollasen document imaging
ED5/ED6 EDMICS (You. With. DOD)
EPS encapsulate PostScript
FAX Fax
Fmv Frame Maker
Fpx Flashpix
GED Arts & Letters (draw)
IBM GDDM GDF format
CompuServe GIF
Gp4 CALS Group IV – ITU Group IV
GX1/GX2 Show Partner
ICA IBM IoCA
ICO Windows Icon
Amiga IFF ILBM
IGF Inset Systems (HiJaak)
IMG GEM paint
JFF / JPEG JPEG format (or. JFIF and JPEG)
KFX Kofax Group IV
LV Laser View Group IV
MAC Mac Paint
MIL See “gp4 "
MSP Microsoft Paint
NIF Navy Image File
PBM Portable Bitmap
PCD Photo CD
PCX PC Z-Soft Paintbrush
PIX See “IGF”
PNG Portable Network Graphics
PNM / PPM UNIX portable bitmap
PSD Photoshop native format
PSP Paint Shop Professional native format
RAS (gridless) SUN
SGI RGB (see “SGI”)
RIA Alpharel Group IV document imaging
RLC Image Systems
Miscellaneous RLE RLE-compressed formats, similar to BMP
RNL GTX RunLength
SBP IBM Story Board
SGI Silicon Graphics RGB
SUN Sun Corp.
TGA Target
TIF Tagged Image File Format
Wpg WordPerfect Image
XBM X Window Bitmap
XPM X Window pixelmap
XWD X Window dump
It should be mentioned that many of these formats are either past, present, or by being so. Most are not available in Photoshop, hence their relevance not elucidated here …
Digital Camera Formats
RAW
All SLRs and a range of semi-compact cameras can save in reformate. This is called global RAW, but says it is Nikon NEF, Canon says in CR2, Minolta MRW at etc. .. These reformatted is unfortunately not compatible with each other, but Photo Shop RAW plugin supports processing of the vast majority reformate. It must be said that Adobe has created a general reformate with open specifications – namely DNG. This format, we will probably see more widespread in the future – already supported by including Pentax K10D.
RAW comes directly from the camera, and as such is unaffected by the camera’s internal processing software, camera software, simply enter draft settings of the RAW file, but the user will be able to change these settings in the preferred RAW editor.
This will also retain the high bit types – typically 36-bit, and you can pay much more dynamic in your images, and even a lower noise level. RAW files turn to turn a lot more than as JPEG.
If you have the option, you should shoot in RAW whenever “it is important pictures we take.” Now almost all the pictures Monday shooting, some potential to become important later, so I am trying to say is – detonating money, buy a pair of 2GB memory card (they are cheap now) or greater, and shoot only in RAW .
The advantages of RAW is therefore:
# Major bit types (12 bits per channel, compared to 8 bits per channel to JPEG)
# More dynamic in the picture
# Option to remove noise more effectively
# Option to remove the objective phenomena such as fringing more effectively
Only downside is as mentioned before, the extra space it takes. If you do not have software available which can thumbnail browse RAW images, you should shoot in RAW + JPEG (which both make a RAW file and a JPEG file for each photo shoot Monday).
JPEG
All digital cameras (except Sigma DSLR) can save the image in JPEG. This format is fine, but you should ALWAYS shoot the highest quality! There is no reason to get pictures with a little amative colors and sharpness are slightly lower, just because it would save 200-300 dollars for a new memory card.
TIFF
Some digital cameras can save in TIFF. Images stored in TIFF may have the same bit types as RAW, but TIFF images do not have the same opportunities as RAW editing. In contrast fills the slightly smaller than RAW, but still a lot more than JPEG.
pixels, DPI and PPI
Pixels in Photoshop (and on screen in general) are the dots, forming the display itself. 1 pixel is the smallest unit a screen can display. Read the rest of this entry »
Introduction
What is Photoshop?
Adobe Photoshop is one of the most powerful tools for PC and Macintosh when we speak imaging and 2D bitmapgraphics. Gimp and Paint Shop Pro is just the biggest competitors, and they do really well. Paint Shop Pro is very cheap compared to Photoshop, Gimp is completely free!
Photoshop is available in an academic license, which for many is the way forward. Moreover it can download a free demo version and you can get a “light” version called Photoshop Elements.
What is a bitmap?
There are usually only 2 digital imaging types, vector and bitmap.
Vector is used as the CorelDraw, Freehand, Flash, and even various 3D programs. Photoshop also has a few vector tools; them we know as the “Shapes”.
Vectors are mathematical equations that describe a line cutting a section through a vector lining. Thus one can scale the image with vector graphics unbridled up and down in size without losing quality! In addition, vector graphics fills little on the hard drive, compared with bitmapgraphics. The disadvantage is that the format can not be used to take pictures, since the organizations of such vectors are not equal can be calculated from the signal from an image sensor.
Bitmapgraphic is as simple as a right: A bitmap consists of a lot of pixels (dots), each of which may have their individual colors.
Each pixel has a basic x-position y-position and one color.
Exactly this is very important to understand when we work with Photoshop – because we can not build things in a picture which does not exist in the image without having to sign them (or copy them in from another picture).
Bitmap fills more than vector, since each pixel must have explained its position and color – while the vector is, as I said just mathematical equations. Therefore invented a wide range of compression for bitmaps; those we come in to later.
Computer requirements
Photoshop CS2, as such, does not require a huge machine to start, but if you want to work intensively with larger files, especially files intended for print, so it is strongly recommended to have at least 1 GB of RAM. Actually, I would recommend 2GB of RAM, so you often avoid the computer is slow because it runs out of RAM on the way, even if you have multiple things running (eg background music from your Winamp or Windows Media Player).
Your monitor should be able to display colors with high accuracy as your pocketbook can handle. Older deep CRT delivers incredibly beautiful color of money – at the time of writing, the visual nature of a much better buy than TFT displays.
TFT displays (flat panel) is a bit trickier; typically the cheap TFT monitors are based on a panel technology called TN +, and is NOT suitable for imaging.
Explanation of link between bits and colors …
Basics of bits
A color image information is divided into red, green and blue colors (RGB) when it appears on the screen. These three colors (Red, green and blue) are the basic colors of light – also known as additive color mixing.
Sometimes seen, However, also be used for CMYK images, it is converted color values to prepare the image to print – but it brings us into the future.
However, there are many different bit types you can work, and while we primarily work with Photoshop 24 bit (8 bits per channel), then bit types important theory to have in place.
Bits & bytes
Bits and bytes are undeniably linked. Bytes used on the size of a file (software) may have, while the bit is the information depth. Relations between them are:
* bits = 8 bytes
bytes / = 8 Bits
This relationship is as valid for the calculation of possible download speed in kB / With (kilobytes per second) according to the specified MBit for your Internet.
Relationship between the number of colors and bits sees something different.
We have 1 bit which can be either 0 Or 1 This can eg be to 0 tells the screen to display white, And 1 tells the screen to show black. So we have 2 options. Mathematical write it: 2 ^ 1 = 2
If we have 2 Bits, we say that the 2 options we had before are now 2 options each. bit – so we get 4 colors because:
2 ^ 2 = 4.
At 8 Bits, we say again:
2 ^ 8 = 256. So 8 bits can display 256 colors.
Consequently will review the bit types we have available in Photoshop CS2.
1-bit images
1 bit is also called “duo tone” Or “Monochrome” because there are only 2 colors. For pure black and pure white.
1-bit images should not be confused with using grayscale typically up to a total of 256 different gradients.
8-bit images
8-bit images contain 256 colors (often 16 color palette basic + 80 gradients of red, green and blue). What colors of these 256 colors will be, one can nevertheless effectively be chosen from a 24 bit palette.
The advantage of 8 bit images is that one can make an “indexed” palette. Notably GIF format is restricted for maximum use of 8-bit color.
When in Photoshop will convert a 24-bit color image to 8 bit (Image> Fashion> Indexed Color …), there are many options – but it is recommended that you use “Local: Adaptive” because this method adjusts the 256 colors you have available to suit the colors used in the picture. In contrast to the flat as “Windows System” Range, just trying to get your picture to look similar basis, using the “Windows System palette.
24 bit images
24-bit images contain 16.7 million colors, also called “True Colors”.
Here we 8bit per color channel (8 bit red, 8 bits green, 8 bits blue) = 24 bits total.
Indeed, all JPEG images in 24 bit, even as Windows is set to display 32 bit color. yes, Actually 24 bit color is that Windows sometimes called 32 bit color! Read on for an explanation …
32 bit images
When we talk about 32-bit color we often 16.7 million colors – that is, it is 24 bit color.
But what is 32 bit color? yes, 32 bit color 24 bit colors with an alpha channel (a extra channel that provides transparency in the picture). 24 bit color is 8 bits per color channel (8bit for Red, Green and 8bit to 8bit for Blue), and the last 8 bits is the alpha channel. Known file formats, which may use an alpha channel (English: alpha channel) are TIFF (. Tif), TARGA (. Tga) and Portable Network Graphics (PNG).
48 bit images
Adobe Photoshop can work with 16 bits per channel, equivalent to 281,474,976,710,656 colors. This is much more than what your computer can display, so that you see on your computer when you work for 48 bit is a converted representation of the real picture, you see it in 24 bit (because your monitor can not display greater color depth than this) but Photoshop makes it possible to work with 48 bit colors.
96 bit images
Adobe Photoshop to work 32 bits per channel, it is called “floating point” (floating point representation calculations). 96 bits are used for HDR (High Dynamic Range) Images, ie. images with extremely high dynamic range, which may prove more dynamic than even the human eye can capture.
When you work in 96 bit, you will often need the ability to preview in Photoshop – Select menu “View”> “32-bit Preview Options.”
NOTE; printable (and less resource-view in general) you must convert to 48-bit (16 bit per channel) or 24-bit (8-bit per channel).
Color Space
To refer to colors, we need to have a system we can refer to them in. Ex. in chemistry have of course the periodic system. In computer graphics, it will be a little more math than that.
Adobe Photoshop can work with all common color spaces.
We will look briefly at the different color spaces. Note incidentally that not all color spaces are compatible with all bit types. For example, LAB can
Color Space: RGB
Logically, giving the most sense for us to work RGB (Red Green Blue), since this is how the screen shows colors (additive color mixing). Thus, we define the colors from 3 values that represent, respectively. Red, green and blue.
To read later in this article how the RGB values defined.
Color Space: CMYK
CMYK for print, while the RGB is used for displays.
CMYK stands for Cyan Magenta Yellow Key where Key is mostly black.
When considered as RGB additive color (ie, colored light), so does the subtractive CMYK colors (eg, like when you mix paint). therefore, extremely well suited for CMYK printing, which colors are mixed correctly from a specified converted color value (from hexadecimal).
If you need an image generated, so you should convert it to CMYK before sending. In Photoshop makes it very simple menu “Image> Fashion> CMYK Color.” This will allow Photoshop to convert your RGB image to the color values as Photoshop estimates, the corresponding CMYK values, and you’ll get a more authentic impression of how your image will look like when it comes out in writing.
Color Space: LAB
Lab stands for Luminance (Brightness) and a + b is the component values, WHERE “A” controls the red-purple <->; green spectrum, And “b” controls the Blue <->; yellow spectrum.
Lab is an absolute color space, ie. the colors are solid here, unlike RGB and CMYK.
Other absolute color spaces include sRGB and Adobe RGB.
When we talk Lab in Photoshop, then it is really CieLAB spoken about.
Color Space: sRGB
sRGB (standard RGB) is an absolute color space based on RGB as we looked at before. sRGB standard is extremely widespread, and although it is primarily adapted (The “old” deep) so that both digital cameras / scanners / TFT monitors also said to go under the sRGB standard.
Color Space: Adobe RGB
Adobe RGB is an absolute color space, based on CMYK as we looked at before; it is a way to reproduce in CMYK as RGB values.
Compared to Adobe RGB, sRGB has improved:
- Cyan-green midtone reproductions
- Orange-magenta highlights reproductions
- Cyan and green shadow reproductions
Hex values
The last part of this article will deal with hexadecimal.
Usually we are working with decimals – that is, We have 0, 1, 2, 3, 4, 5, 6, 7, 8 And 9 — and from these 10 numbers, we can create both small and large figures and define committal until we get tired of your hands.
There are also binary subsystems that use computers, but we will not examine in this article.
Hexadecimal is a 16-representation system. Instead of having invented strange new mug duller, so have chosen to use the first six characters of the alphabet – that is, A, b, C, d, e and f.
Now we are both 0-9 and making good when we simply type a number!
So we see therefore that:
| Decimal |
hexadecimal |
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 4 |
| 5 | 5 |
| 6 | 6 |
| 7 | 7 |
| 8 | 8 |
| 9 | 9 |
| 10 | A |
| 11 | b |
| 12 | C |
| 13 | d |
| 14 | And |
| 15 | F |
As we see, so we write as simply f instead of 15
Hexadecimal variable used in computer graphics, to define the colors with.
Colors are defined as follows:
Each basic color in the additive color mixing (Red, Green, Blue) can be defined with a 2-digit value, where each digit can be between 0 and f.
When we look across the hex value, then there is the three basic colors are each defined by 2 digits. So we have a total of 6 digits.
We mention first red, then green and finally blue. Abridged; RGB.
# 000000 has the lowest value and provides pure black.
# Ff0000 is pure red, because we have put the two digits for red, the highest possible values.
# 00FF00 is pure green, because we have the two for green, the highest possible values.
# 0000FF is pure blue, because we have put the two digits for blue, the highest possible values.
# ffffff is pure white, because we have all the digits on the highest possible values.
In Photoshop, you can see hexvarient when you click the palette:
A hexvariant is easy just to pass on to others – as it is both easier and more precise to say / Write: # Ff9900 instead of “orange”. Those who need hexvariant can simply enter hexvariant in its graphics program!
RGB values
Also RGB values are used widely. In Photoshop you’ll see them in the palette:

R stands for Red (Red), G stands for Green (Green) and B stands for Blue (Blue).
A value of R, G or B, can be between 0 And 255 Remember our 24-bit scale before: 3 channels, which are divided by 8 bits for each basic color, corresponding to 256 colors. 0 to 255 gives the total of 256 Figures! Because we assume that we work in 8 bits per color channel, so says this exactly RGB8.
The RGB values equal 255 equal to hexadecimal ff.
Let us look back at our hex values; f corresponds to 16 value (ie, figure 15). When it says later that it is the highest number of options, ie. 16 ^ 2 = 16 * 16. And 16 times 16 gives 256 so the corresponding RGB value.
Or, yes, 256 is not equal to 255 But we have not talked to 0 when we say 255, So 255 is actually seen the 256′ende value (like when you are born – then you are indeed in your first year of life, even if you are 0 years old).
Many programs use RGB values to define their colors, and Photoshop can use both the hexadecimal and RGB values.
Syntax of namespace
In an XML document refers to a namespace using a special attribute (xmlns) associated with the root element, as in the following example:
| <article xmlns=”http:/ / www.goodtutorials.org / xml / article”> |
This indicates that the feature article and its sub using the names defined in the namespace identified http:/ / www.goodtutorials.org / xml / article identification.
The identifier of a namespace can be represented by any string, provided it is unambiguous. Just to ensure consistency, long-standing practice is to use a URI (Uniform Resource Identifier) as an identifier.
It should be stressed that it is not necessary for the address specified as a namespace identifier corresponds to a file published on the Web, it is simply used as the identifier and the parser does not access the Web to verify the existence of the URL.
To report a namespace with the XML Schema should be stated in the root element as in the following example:
| <item xmlns: xsi = “http://www.w3.org/2001/XMLSchema-instance” xmlns = “http:/ / www.dominio.it / xml / Article” xmlns = “http:/ / www.dominio.it / xml / bibliography” xsi: schemaLocation = “http:/ / www.dominio.it / xml / Article articolo.xsd ” xsi: schemaLocation = “http:/ / www.dominio.it / xml / bibliography bibliografia.xsd ” > |
The attribute xmlns: xsi specifies the way in which it is indicated the reference to the diagram, while the attribute xsi: schemaLocation is the namespace and the file where you defined the XML Schema separated by a space.
And can combine multiple namespace so that each element is used that relates to your namespace.
Remember that when we refer to a namespace, this reference applies to the current item and all items included, unless you specify a different namespace.
The following example uses elements taken from two different namespaces: one for the grammar of the structure of an article and the other on the grammar of bibliographies:
| <article xmlns=”http:/ / www.goodtutorials.org / xml / article” title=”Guide to XML”> <paragraph title=”Introduction”> <text> blah blah blah </ text> </ section> </ year> |
Include reference to a namespace for each element is usually uncomfortable and makes it difficult to read the XML document. You can create abbreviations to refer to the namespace.
These abbreviations are made up of alphanumeric characters followed by a colon (:) as declared in the root element and used as prefixes of the names of the elements. The following example shows the XML code above the use of these prefixes:
| <article: Article title = “Guide to XML” xmlns: art = “http:/ / www.goodtutorials.org / xml / article” xmlns: bibl = “http://www.goodtutorials.org/xml/bibliography”> <art:paragraph title=”Introduction”> <art:text> <art:paragraph title=”bibliography”> |
The declarations xmlns: art and xmlns: bibl assign prefixes art: and bibl: their namespace prefixes, and these are used for each element of the XML document.
Integration of grammar and namespace
Starting with a grammar defined by an XML Schema, you can use a validating XML parser to check the validity of an XML document. The parser will need, therefore, both the XML document to be validated, the XML schema is compared with which to validate.
There are several ways to provide information about the parser to be used for validation. One of these ways is to document a reference to the XML schema to be used. This reference is associated with the root as in the following example:
| <item xmlns: xsi = “http://www.w3.org/2001/XMLSchema-instance” xsi: noNamespaceSchemaLocation = “articolo.xsd”
title = “Guide to XML”> |
In addition allìattribute title were added two predefined attributes.
The attribute xmlns: xsi indicates a URL that specifies the manner in which they indicate the reference to XML schema. The attribute xsi: noNamespaceSchemaLocation indicates the name and possible location of the file containing the XML schema reference.
One of the characteristics desirable in creating a new language is the ability to integrate elements from different grammars. This feature allows you to reuse parts of grammars already defined by not having to redo the work already done in other areas.
In this way, For example, it would be possible to integrate a language for the description of technical articles with a pre-existing language for the description of bibliographies, obtaining a new language composed. However, The composition of languages poses at least two types of problems:
* A document that uses two grammars has the problem of validation: a pattern which reference should be made to validate an XML document “hybrid”?
* Two languages may have tags and attributes with the same name, even if used in different contexts: how to solve this kind of ambiguity?
The solution to these problems comes from the namespace. A namespace is a collection of names of elements and attributes names uniquely identified by an identifier.
The unique identifier identifies the set of distinguished names from any other namespace names. For example, if in a grammar to describe the data you have defined an address, this name could be confused with the address element defined within a grammar that describes e-mail messages. The identifier for the namespace for differentiating between two homonyms.
The concept is not new in information: for Example, when we define the field names in a table in a database we have defined a namespace. We can not have fields with the same name within a table, but we can have the same names in different tables. We can resolve the ambiguity between two homonyms precede them by the name of the table (the namespace).
As part of XML technologies, an XML Schema defines an implicit namespace elements and attributes that can be used in an XML document.
If in an XML document using elements defined in different schemas, we need a mechanism to identify each namespace and the XML Schema that defines it.
Declaration types
XML Schema provides the opportunity to make the definition of the modular structure of an XML document through the declaration of types and elements. Read the rest of this entry »

