Amiga Collections: MegaDisc/MegaDisc 06 (1988)(MegaDisc Digital Publishing)(AU)[m][WB].zip/MegaDisc 06 (1988)(MegaDisc Digital Publishing)(AU)[m][WB].adf/ARTGALLERY/PaintHints

Text File | 1988-04-09 | 16KB | 333 lines

     COMPUTER GRAPHICS

     Some Hints on How to Improve Your Graphics

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     [ED. NOTE: This is an article by Henk van der Graaf, painter of
     "Tiger" on MD5, and of two paintings on this disk. He lets us into
     some of his trade secrets for getting some of his remarkable effects,
     from a practical point of view, and I'm sure that anyone even
     vaguely interested in computer art will find much of interest here.
     It is also worth examining his paintings in DPaintII with the
     magnifying tool, to see these techniques in practice. The two on
     this disk are med-res graphics, so shouldn't strain your memory as
     the "Tiger" does when in DPaint.]

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     Here are some hints for those of you who would like to improve your
 technique when making your own illustrations, for example paintings and
 title screens on the Amiga.

     I would like to stress the point that this article will not turn
 you into an instant artist as the subject is technique, not art.

     The computer as a medium for creating graphics has some built-in
 problems. However, let it be known that other mediums such as oil-paint,
 watercolour, ink, and crayon just to mention a few have just as many
 shortcomings and limitations.

Some of the shortcomings of computer painting are:
  i) the limited number of colours
 ii) creating gradual shading or flow of colour
iii) putting in extremely small details
 iv) the step effect created by lines that are  on an angle
  v) expression of material e.g. hair
 vi) the screen (canvas) size

     Some of these problems along with some others will be dealt with in
 the course of this article.
 The painting programmes that I use most are DPaint II, and Aegis Images.


CREATING A WORKING DISK

     If you  don't want to go to the trouble of creating a formatted
 blank disk with a directory for the images, you  have to make enough
 disk space on the disk with the painting programme to save your creations.

 Do not modify your original disk; make a copy of it. Then, from the copy
 delete those parts of the programme that you won't be using. Enough space
 can be created on Aegis Images by deleting all the paintings. From DPaint
 II delete the resolutions not used and the different types of brushes.
 It is possible to delete more than I have indicated, but for the time
 being this is sufficient.


CHOOSING YOUR OBJECT

     Care should be taken in choosing your object to be painted. The
 two biggest pitfalls are small details and the need for too many colours.

     Start off by choosing a painting that has no more than one or two
 objects. It will help you to cope with the limited number of colours at
 your disposal. For this exercise I would choose a flower as most
 flowers are of a single colour, and basically you will need only two
 colours, one for the flower itself and one for the stem and leaves. The
 other 14, or 30   colours left, depending on the resolution you are
 using (more of that later) can be devoted to shading, highlights, and
 shadows.


TRANSFER OF OBJECT TO THE SCREEN

     I suggest that you copy an existing illustration to start off with
 because there are enough technical problems without creating artistic
 ones as well.
     Having chosen your object to copy how do you get the outline and
 details onto the screen? If you are painting from a photograph, postcard,
 magazine, or book you are faced with the problem of transferring the
 image to the screen preferably without damage to the original.
     Both DPaint and Images have a grid-tool that will help you to create
 a screen that looks like graph paper. Using this grid-tool create a
 grid where both the vertical and horizontal lines are approximately 10
 mm apart on the screen.

To get the grid for Aegis Images:

  i) Activate "Special-Effects Menu"
 ii) for low-res change the horizontal and vertical numbers each to 30,but
     for med-res change the  horizontal  number to  30 and  the vertical
     number to 15.
iii) Activate "Show" to look at the set grid pattern.
 iv) Deactivate the "Show" grid pattern by clicking the left mouse button
     anywhere on the screen.
  v) Activate  both  the  "HGrid" and  the "VGrid" (they will both  be
     highlighted in red) and then "OK" the "Effects Menu".
 vi) The next "Effects Menu" will appear and "Grid" will show red. Also
     "OK" this menu.
vii) Choose the straight line-tool and draw up your grid. (The programme
     will only allow you to draw the horizontal and vertical lines that
     were previously shown when that particular grid was displayed in the
     "Show" mode.)

To get the grid for DPaint II:

 i) Activate  the grid-tool  with  the right mouse button and change the
 requester numbers to the same as those given above for Aegis Images ii).
 ii) Activate the dotted-tool. You should get dots spaced 10 mm apart by
     moving over the screen keeping the left mouse button down. Connect
     those dots with the straight line-tool.

     Go back to the screen and count the number of whole squares from
 top to bottom. Do not count the incomplete block at the top and the
 bottom.

     Next, go back to the picture and measure the height only. Divide
 the height by the number of vertical squares that you have counted on
 the  screen. For Example: picture height 260mm, number of squares  on
 the screen 13. Divide 260mm by 13 screen squares = 20mm. Divide your
 picture  now by drawing vertical lines 20mm apart. If you do not wish
 to damage your picture stretch  a sheet of tracing paper over the top
 of it and do all line work on the tracing paper.

 Number the row of blocks along the top starting by  placing a 1 (one)
 in the block on the left.  Number the row of vertical blocks on the
 left hand side starting by placing a 1 (one) in the block at the top.
 The number 1 (one) will be common to both the vertical and horizontal
 rows of blocks.

     Go back to the screen and with the freehand-tool write in the
 numbers corresponding to those on your picture. Make sure that the
 numbered grid is in the centre of the screen. (When finding the middle
 line of the screen don't forget the part under the palette.) Rows of
 blocks on the right and left of the centered grid can be deleted.

     If your picture happens to have more horizontal blocks than the
 screen has you will have to decide which part of the picture horizontally
 is most important to you. This, however, does not happen very often.

     Now draw the outline and details by looking at the picture and
 drawing lines in the corresponding blocks. The numbers at the top
 and bottom of the screen and the picture will help you to identify
 corresponding blocks.The mouse is not the ideal tool for drawing, but
 the outline does not have to be perfect. If you have chosen a face or
 head make sure the important details such as eyes and nose are in the
 right place.

     When you have finished with the outline and details remove all the
 grid lines by using the background colour. My use of colours, in most
 cases is black for the background and cream-white or brown for the line
 work and grid lines. Background colours other than black are likely to
 interfere with colours in the picture and white line work is hard on
 the eye.


CHOOSING YOUR PIXEL SIZE

 Low resolution (lo-res), medium resolution (med-res), interlace, and
 high-resolution (hi-res).

Lo-res
         Screen size - 320 x 200 pixels
         32 colours
         No interference of adjacent colours
         Not much memory required
         Picture will take about 10 to 20k of disk space

Med-res
         Screen size - 640 x 200 pixels
         16 colours
         Some interference of adjacent colours
         Memory requirement within the range of the 512k, but saving your
         work at hourly intervals is recommended
         Picture will take about 30 to 60k of disk space

Interlace
         Sreen size - 320 x 400 pixels
         32 colours
         All other details are similar to med-res except for an annoying
         flickering effect of those parts of the painting that have sharp
         contrasting colours

Hi-res
         Screen size - 640 x 400 pixels
         16 colours if you have one megabyte of memory
         Total interference of colours
         Has the same annoying flickering as interlace
         Picture will take up to 120k of disk space

     If you are about to start your first picture I would recommend using
 lo-res. After a few lo-res pictures you can progress to med-res. The use
 of interlace and hi-res (one megabyte required) have advantages, but the
 forced use of an anti-flicker screen or a special monitor to combat the
 flickering effect is a high price to pay. The anti-flicker screen only
 subdues the flickering, and alters the colours. The high sustain monitor
 is expensive and at this moment difficult to get.

     The interference of adjacent colours can be very useful.
 Dots of white and red next to each other will result in pink.
 Two white dots with one red dot on the side will give white with a pink
 edge.
 Five shades of grey with one red (6 basic colours)  will result in 15
 colours - 1 red + 5 shades of grey + 5 combinations of red with grey +
 4 further combinations of grey.

     I will leave it to you to figure out the total number of combinations
 possible with 16 colours.

     After a few lo-res paintings to get used to the painting tools and
 disk handling, the obvious choice will be med-res which has twice the
 number of pixels  and, as shown in the exercise above, more  colours
 than the  32 of lo-res.

     Up to this moment I have not mentioned such programmes as Digi- Paint
 or Photon. These programmes are excellent and certainly have their use.
 Digi Paint allows the use of 4096 colours, but is extremely slow. Both
 Digi Paint and Photon have the disadvantage of inserting an additional
 colour if the contrast between the chosen colour and the background
 colour is too great. The computer added colour is difficult to control
 and creates effects that might be undesirable. However, for those of you
 who want to modify digitized pictures they are a must and highly
 recommended.


CHOOSING YOUR PALETTE

     The choice of the palette is probably the most important step. A
 bad choice of colours will result in a continuous struggle for more
 colours. Because there is no interference from adjacent colours with
 lo-res care should be taken to ensure that besides the basic  colour
 chosen for your object you  have 2 or 3 shades that are lighter and
 darker than it. This will make it easier to create shadows and highlights.
 The computer programmes have a feature called "range". After you specify
 the darkest colour and say 5 colours away, the lightest colour,
 the programme will select the in-between colours. To modify the DPaint
 palette press "P". To modify the Images palette go to the colour menu
 and select "colour". By clicking with the left mouse button on
 the colour to be changed you can alter the colour with the RGB-controls.
 All 16 or 32 colours can be changed, but care should be taken with some
 of the colours as they are basic to background, lettering and borders.

     In med-res the choice of palette colours is more difficult. Because
 only 16 colours are available it is very important that every colour can
 be used to create several other colours. For example, white with dark
 green could cut out the need for light green. Some experimentation
 on a free part of the screen will help you to decide.

     Because I do not know what you are going to paint I can only give a
 typical palette. It should contain black and white and at least 4
 following shades of grey and brown. Since grey and brown are not very
 strong and are easily overshadowed by the prime colours (red, blue and
 yellow)  their effect will result in darker and lighter shades of the
 prime colours so essential for good shadow work and highlight details.

     It is for this reason that the med-res palette is much more difficult
 to establish than the lo-res palette. Don't be afraid to go back to the
 palette menu if after some time you find the need for some colours to be
 modified.


CREATING YOUR MASTERPIECE

     At this stage we have an outline of the picture, and a palette. If
 you wish to use the spray-paint tool this is the time to use it. Spray
 painting can be very effective for some backgrounds. Choose a "spread"
 that is not too big, and limit the numb er of dots. Give the background
 the basic colour you want it to be and spray the desired pattern. If you
 do not use "masking" of your major object the limited spread and small
 number of dots will prevent too  many unwanted dots getting into your
 object.
 Also, staying away from the object and imitating the spray pattern close
 to it using a single pixel brush will help.
 If using more than one spray colour use the darker spray at the bottom and
 the lighter one at the top. The dark colour will work as a foundation.
 However, if you use spray for sky the darker colour should go to the top.
 It will give the painting depth.


     Filling in is the next step. Before you use the fill-in tool make
 sure you do not have any breaks or gaps in your outline. You can check
 for  breaks by using the magnifying-tool. If you overlooked a gap and
 part of the painting that you didn't want to fill-in gets filled-in,
 use the UNDO to remove it, close the gap and try again.
 After filling-in all the basic colours check for details that are out of
 place.

     Most of the shading in lo-res can be obtained by using a progression
 of colours. In med-res better results are obtained by using a basic
 colour and a progression of darker brown dots for red, yellow and green,
 and grey dots for white and blue. At the cost of time you can create a
 checkered pattern. It could for example be made up of red and brown
 squares. By progressively using darker browns the red will also darken
 by the influence of the brown. The brown dots can't be seen as the red
 is the mo re dominant colour. It will appear that the red gets darker,
 creating an illusion of a shadow. Using two shades of red will extend
 the range from light to dark even further.

     A typical annoying feature of computer graphics is that lines on an
 angle and curves have little steps. Most of these steps can be eliminated
 by putting in an intermediate colour. For example, if the object with the
 steps is red and the background colour is black put brown dots in
 the corners of the steps. The ragged outline will then be smoothed out.

     Most of what has been said here can be seen by scrutinizing my two
 paintings on this disk. Both of the paintings are med-res and they can
 be transferred to a painting programme to be looked at with the
 magnifying-tool.


BACK-UP

     Finally, I would like to advise you to save your work each hour. By
 running out of memory an afternoon's work using med-res with 512K of
 available memory can be lost. Also, at the end of your day's work make a
 back-up copy. Detailed paintings can take several days to complete.
 To lose a painting because of memory or disk failure can be very
 disheartening.


 Please note that I will be glad to answer any further questions you may
 have. In the first instance direct all mail or calls to Megadisc.

                                           Henk van der Graaf

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