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vectorial image versus points


Graphical design with the PC

Maps of Points and vectorial drawing

 All we know that, among other things, the computer allows us to make more or less sophisticated drawings, but use all the same techniques. If we have a program of map of points we can make a figure (for example a circumference) without more problem than to place a point next to the other so that the distance to the center is more or less equal.

 If we have a program of vectorial design, the thing changes, because what it solicits to us the program is the center of the circumference and the radius, drawing up of automatic form the circumference That happens if we want to extend the image with the zoom lens.

As one is in the figure of the left, the A drawn up with maps of points (To of the right) begins to show pixels that compose the image.

Nevertheless, the vectorial image (To of the left) does not show this error Exists another enormous advantage. If we want a figure, example a doll, and we do it with a program of points (example the GIMP or Photoshop) when extending the image we are going to have the doll with the contour marked by pixels.

 This is not very well. Approach you the TV of your house and observe as the images are seen if you approach much.

 In the case of the vectorial programs, the thing changes. If we want to extend the doll, when being formed by mathematical formulas (the circumference by the center but radio, the line by the starting point and final, etc), the formulas are only going away to mold to which we solicitd, that is If we extended to 100%, the program knows that the head that before it had, for example, a radius of 2 cm must happen to a radius of 4 cm. Once changed the radius becomes to draw up the perfect circumference.

Of this form one takes control of all the geometric figures that conform the doll. To this one says to him that they are ESCALABLES, that is to say, that they can increase or be reduced without loss of quality.


Pixel as a point of a digital image is defined.


Once realised the drawing, it is necessary to keep it as a file whose letters after the point will tell us that type of file is, for example  


figura.png, figura.jpg or figura.gif are archives of type map of points figura.svg is a file of vectorial type


I number of elements that contain if it is a vectorial image

In the case of photographic adjustment or very complex designs the use of programs of points is better


Just a little bit of quality, please

 In an image of maps of points both factors that influence in the quality are the depth of the color and the resolution defines resolution as the number of DPI (of brief form ppp) that the image represents.

 details of digital chamberThis is just like to say to whatever pixels (1540, 300, 600, 72. ) it has in one inch. We remember that the inch is equivalent to 2.54 cm.

In the case of the resolution of digital cameras, to obtain the resolution one multiplies pixels of width x pixels of stop. If our camera can obtain 2000 xs 1500, megapixels gives a resolution us of 3.

If later we must remove the photo in paper, we needed to know that resolution of impression has our printer, that is to say, the DPI (ppp) that can be printed the digital photo.

 It is considered that from 200 ppp (200 pixels in 2,54 cm) the resolution of impression is good. That maximum paper we can use. That is, if I want to remove the photo with the quality from the camera,  what maximum format I can have.

For them to be divided the width of that image (2000 in our case between the resolution of impression 200, 2000/200 = 10 inches).

 That is that but of 25.4 cm we cannot use not to lose quality. If majors are used, the quality will be harmed.

The professional cameras use devices that are able to obtain images with the highest resolution, so that soon we can have those photos in great formats of paper with the maximum quality.

 In the camera of above we have as elements more important the objective, ordered “to pick up the light” of the best possible way. 

 It can be great an angular one, one for taking of distant images, etc.

 The Stopper is a mechanical device ordered to pass the light to the sensor. He is very fast so that the photography does not leave blurred. The sensor and the processor are the fundamental electronic components.

 First it transforms the light into electrical signals and the second it transforms those electrical signals into the file of the image, that will be recorded in the memory of the camera. depth of colorThe depth of the color indicates the number to us of colors that we have.

Of course, greater better number of colors is the image and more similar it is to the reality. In order to define the bits (0 and 1 of the digital language) For a depth image with 0 and 1of a bit are used it we will have two colors (black if the bit is 0 and white if he is 1).

If we have two bits, the possible combinations are 00, 01, 10 and 11, therefore only 4 colors (this is not used and it is only indicated as example) For 8 bit, or what a Byte is the same, we have 2 high to 8 combinations, that make a total of 256 colors If we used 24 bits (that is 3 bytes, one for each basic color) we obtain but from 16 million colors.

In order to obtain the possible number of colors on the basis of the depth of color, we used the formula Number of colors = 2 elevated to the depth   The archives of major of colors (depth) and a larger number of pixel will have a greater size. We already know that but DPI better the image will be seen and if in addition each point has a good depth of color, more quality we are going to have, but all this is going to suppose that the file is going “to weigh” but.

 We already saw that a Byte is the set of 8 bits. (with a byte any symbol of the keyboard can be represented) It can be that the letter to is represented by the 10010011 that is we used 8 bits In the case of the photography, the size usually is moderate in bytes and not in bits.

calculation weight of a graphic file

As the number of bits that it uses a photo will be the number of points that it has multiplied by the bits that each point has (depth of color), we have


More common graphical archives


One of the most common errors is to try to open a file with applications that are not the adapted ones, for example, tries to open to a file doc with GIMP.

 Our work is vital to know the format the image file if we are going it to put in Internet, since many navigating ones only recognize certain formats as they are jpg or png.

 Others as tif, are very good to store images with high quality and are used for impression, but they are not seen in the navigator.

 In the table down are but important although some of them, as SVG is created by specific applications (inkscape). The others can be created by many programs of graphical design

extension of    file

* Type

visible for navigation

tablet png MP If
If bmp MP IF
If jpg MP IF
duck donall


Many others exist, but we are only going away to center in most important with application in our activities of 3º THAT handling the applications that we have in the classroom To the left a file GIF, type of file that allows the animation

 Type: V is vectorial and MP is of the Mapa type of points


Digital file compression:

 If the destiny of the image is to show it in Internet and the Web has many images can happen that the page takes in loading itself and for this reason, some formats take associate systems of compression. Also it happens with graphical archives when using the digital camera, allowing but photos in the memory card.

 Basically two systems exist: * Without lost of quality: Thanks to the use of mathematical formulas applied to the images, they are compressed without lost of quality when reconstructing it. Example of them is archives GIF. * With lost of quality: In this case lines of the image are eliminated.

The percentage of compression determines the lost line number, that does not get to recover when reconstructing the image in the computer. They are used in the archives jpg. Creation of digital images We are going to put hands to us to the work and the best form to see this section is to realise a doll with one of the programs of Open office, Draw call In Draw, the images are realised being based on basic forms and they are united and grouping to obtain complex others but. Activity in group in two Abre the Draw program and realises a doll that has the greater possible number of details. The best one of the class will be exposed in this Web in addition to having an extra point.

  logo of gimp

Photographic adjustment

 Whichever times we have heard speak of which the image is altered in this or that one famous person. We always talked about to photoshop but we consider that a license of this program costs but that the PC that we used, alternatives as GIMP especially are thanked for.


To the left we have a logo of this program that is very used in the subject of Computer science of 4º that With the same we can make many activities handling images of points. The objective of this section is only to present it and to invite to that it unloadings to you from the official page and we alter some of the images that you like more.


Activities 1º On an image of Internet, to apply some of the filters of the program 2º Toma another image from the Web and manipulates the colors 3º Intenta to change the color of the eyes to some character  

example of image realised with CAD

CAD CAM and FALLS 1º CAD are the abbreviations of Computer Helped Design or as Computer assisted design. Its function is to realise designs of pieces for its application in the industry. 2º part is calls CAM (Computer Helped Manufacturing) that is manufacture attended by the computer. Machines of numerical control exist designed to make pieces, using programs CAM and without the intervention of an operative one (except in the use of the program. Therefore, it is designed, one goes to program CAM and this it starts up the machine so that it makes to us what we have designed Are programs as QCad that makes the two tasks simultaneously,


If what we want it is to simulate as is possible to be tolerated a piece that we have designed without spending nothing of material, we used the programs FALLS, that mean Computer Helped Engineering, or in Castilian Engineering attended by computer.

This type of program allows to consider how the piece in aspects as deformations can behave, thermal mechanical resistance, behavior, vibrations, etc   without the necessity to make it. The left a piece imagines around which a fluid circulates. The lines of colors indicate the temperature of the walls of the piece.


If a very hot point is detected (red) can represent a weakness in the piece and surely all “goes away that way”. In order to finalize, to realise the activities of Computer science

Design PCB