No part of this product may be reproduced in whole or part by any means without written permission of the publisher. Unauthorised hiring, renting, lending, public performance or broadcasting of this product or its parts is prohibited.
David Pilling supplies
Ovation Pro
Colour Supplement
under licence for use by the purchaser on one computer at a time. Please write or phone for details of multi-user licences.
While every care is taken, the publisher cannot be held responsible for any errors in this product, or for the loss of data or consequential effects from the use of this package.
This user guide describes the facilities provided by
Ovation Pro
Colour Supplement
. This supplement is provided in the form of an optional extension applet, which must be installed before it can be used.
The applet is called
!ColSupp
It must be copied into the directory
!OvnPro.Applets
, and then
Ovation Pro
must be re-run.
1.2 Litho Printing
After completing and checking your document, the
rst job is to have it typeset. This involves printing the document to a PostScript
le and sending it to a typesetting bureau
(see 1.7)
. Occasionally, a bureau will accept
Ovation Pro
les directly.
The bureau will print a very high quality
original
of your document using an imagesetter.
For high quality or full-colour work, they will usually produce
. This can be used directly to make the printing plates.
A cheaper alternative is a
bromide
(photographic paper), which needs to be photographed to produce the printing plate. This is often called
camera-ready copy
Your printer will be able to tell you which is the best material for a particular job.
Proofs
For full-colour work, it is essential to proof your work before it is printed. A proof is a high quality colour print produced directly from the set of four
lm separations. The two dry-proo
ng processes that are often available are called
Cromalin
and
Matchprint
proofs. They are quite expensive, but allow you to check that everything is correct before the more-expensive print job commences.
Ask your bureau which proo
ng process is available, and how much it will cost.
Printing
A litho press uses a printing plate wrapped around a revolving cylinder. The printing plate, which is presensitized with a light-sensitive coating, is placed in contact with the
lm and exposed to high-intensity light. After exposure the plate is treated with an emulsion developer leaving a hard image on the plate, which is then treated with a greasy medium.
After being mounted in the press, the plate is
rst dampened and then coated with ink. The areas coated with grease attract ink, while water on the areas not to be printed, repels ink. The ink is then transferred to a rubber blanket cylinder, before being transferred to the paper.
The process is often called
offset
litho printing because the printing plate does not come into contact with the paper.
Colour Printing
The process described above prints one ink onto the paper. To print another ink, the operator has to change the plate, change the ink and then print onto the paper for a second time. This explains why two-colour spot printing is cheaper than full-colour printing using four inks.
Some printing presses can print more than one ink at a time, but due to the more complex setting up required, they are normally only economical for long print jobs.
1.3 Spot-Colour Printing
If your document only needs to use two or three basic colours, you can print it very economically using
spot-
colour printing
. If you want to print using the full range of colours, then you should use
colour printing
Spot colour work is simpler to achieve than full-colour work, and two or three spot-colour work is always cheaper than full-colour work.
First you need to decide whether you want to print with two or three colours. Using three colours will be more expensive, but will give a greater scope for designing the document.
Note that in addition to the basic colours you can use any number of tints of those colours. For example, if you are doing a two-colour job using black and red, you can use greys and pinks.
Use the
Edit colour
dialogue box to created named colours for each of the spots (in the example above, both black and red already exist), and for each colour choose the
colour
option at the bottom of the dialogue box
g. 1.1)
Specifying Colour
When you print spot-colour separations, each basic colour and any tints are placed on a separate plate. It is essential for you to tell the printer the precise colour to be used for each plate. You can do this by choosing colours from a standard swatch.
Spot colours de
ned in
Ovation Pro
are used for the screen display only, so it doesn
t matter if they don
t match the eventual printed colour. However, in order to help you visualise what the printed document will look like, it is useful to de
ne the screen colours to match the printed colours. You can do this by de
ning colours using CMYK values obtained from colour swatch you are using.
In order for the printer to know the colour of each plate,
Ovation Pro
prints the colour name at the top of each separation. Therefore, it is useful to set the
Ovation Pro
colour name to the name given on the swatch.
1.4 Full-Colour Printing
In printing, most colours can be reproduced by mixing the correct proportions of the three process colours - cyan, magenta and yellow. Black and greys can be reproduced by combining equal amounts of cyan, magenta and yellow, but in practice this gives poor results, so a black ink is also used to add
ner detail and greater density.
When you print separations, any colours that have not been designated as spot colours will be separated into CMYK
components. When the CMYK separations are printed, they will combine to reproduce the colour of the original.
Tint Charts
When full-colour printing, your document can use any colours de
ned using the
Edit colour
dialogue box. However, the eventual printed colours may differ from those viewed on the screen
(see 1.5)
. It is therefore essential to select colours from
tint charts
A tint chart usually shows samples of over a thousand tints made up from cyan, magenta and yellow. Once you have found the colour required, you should read the cyan, magenta and yellow values from the chart and use them to de
ne a colour in
Ovation Pro
. The chosen colour may not look correct on-screen, but provided it has been de
ned using the CMYK
model, the printed colour should match the colour in the tint chart.
1.5 Colour Correction
RGB to CMYK Correction
In order to print RGB (and HSV) colours used in
Ovation Pro
documents in a full-colour process, these colours must be converted to CMYK. A simple translation that assumes process inks used in printing are the inverse of RGB light, gives inaccurate colour reproduction.
Ovation Pro
provides a correction system that improves this.
Before printing full-colour separations
you should select the
Use correction table
option on the Colour Choices dialogue box
g. 1.2).
When this is selected,
Ovation Pro
uses a special algorithm and separation tables to apply correction
when converting RGB colours to CMYK colours.
Note that this does not affect colours de
ned using the CMYK colour model. Nor does it affect spot-colour printing.
Use correction table
submenu allows different separation tables to be chosen for different typesetters. The default table,
TypeSet
, should be suitable for most situations.
Alternative compatible tables can be added by copying them into the directory:
!OvnPro.Applets.!ColSupp.Resources.cmyk
CMYK to RGB Correction
Ovation Pro
provides a system to improve the display of CMYK colours (intended for output to a four-colour press) on an RGB colour monitor.
To enable this feature, choose
Use inks to display CMYK colours
from
the Colour Choices dialogue box
g. 1.2).
Note that even though this does improve the accuracy of CMYK colours on-screen, you should not entirely rely on the colour you see on the display. For precise colour reproduction always specify colours using CMYK values chosen from tint charts
(see 1.4)
The sub-menu provided above this option allows you to choose different ink mapping
les that control how RGB is mapped to CMYK for different printing processes. Currently only one ink mapping
le is provided
. This is for SWOP printing (Standard Web Offset Printing).
Note that currently the ink mapping
le is only used for converting CMYK to RGB, not for separating RGB into CMYK.
1.6 Preparing Your Document
Overprinting
Overprinting
is used to compensate for misalignment of printing plates during printing.
Suppose your document contains some black text printed on a cyan background. The black plate will contain the black text
g. 1.3)
. The cyan plate will contain the cyan background with a
knock-out
for the black text
g. 1.4)
If the document is printed with the plates exactly in register, the black text will be printed exactly over the white
knock-out
g. 1.5)
. However, if there is misregistration, thin white gaps can be seen around the text
g. 1.6)
. This problem doesn
t just happen with text, but applies to all overlapping objects.
Overprinting helps solve this problem by preventing the background from being knocked-out. So in the example above, the background is printed solid cyan without the knock-out, and the black text is printed on top of the cyan.
This generally only gives acceptable results when printing relatively opaque inks, such as black. Overprinting less opaque colours, such as yellow, may show a colour shift when overprinted.
Colour Level Overprint
You can specify that a particular colour will overprint by choosing the colour on the
Edit colour
dialogue box and then choosing
Overprint this colour
from the
Overprint
dialogue box
g. 1.7)
Overprint limit
speci
es the tint above which an object colour will overprint its background. So the default value of 90% means that overprint will only occur with tints of 90% and above. This option prevents lighter tints, which are less opaque, from overprinting.
Object Level Overprint
You can specify that a particular object will overprint by choosing
Overprint
on the colour picker when applying colour to an object
Font Mapping
If your document uses RISC OS fonts for which there are PostScript equivalents, use
!FontPrint
to map the RISC OS fonts to the PostScript fonts. This is the recommended procedure, but only if your bureau has the font you require. Note that the PostScript printer driver contains default mappings for many standard fonts, so it is unnecessary to map Acorn fonts such as Corpus, Homerton and Trinity.
!FontPrint is an Acorn application supplied with RISC OS, and can usually be found in the
Printing
directory of your hard disc.
Any unmapped fonts are written into the PostScript file and temporarily downloaded to the typesetter for the duration of the print job. This will increase the size of the PostScript file, but it allows any Acorn font to be printed even if there isn
t a PostScript equivalent.
Note that you should not use the
Download
option provided in
!FontPrint
. This downloads RISC OS fonts to the typesetter whenever !Printers is started. These take up large amounts of memory, which is not released even after the file has printed.
Ovation Pro Page Size
Set the required page size in
Ovation Pro
using the
Page guidelines
dialogue boxes.
The maximum page size that you can typeset depends upon the typesetting bureau you are using. You should have no problem up to A3, but above that you should check the maximum width with your bureau. Remember that printers marks increase the overall dimensions by 14mm.
Printing JPEG
Ensure that your document does not contain any JPEG images.
RISC OS 3.6 and later allow JPEG
s to be loaded directly into
Ovation Pro
without being converted into sprites. Since these JPEG images are stored in compressed format,
Ovation Pro
cannot produce colour separations from them. For this reason, you must convert JPEG
s into sprites before loading them into Ovation Pro.
Printing Pictures
You can set half-tone screen information for the selected picture by choosing
Picture
Screen
to display the
Halftone screen
dialogue box
g.1.8)
. The options in this dialogue box are intended for experienced users, and should not normally be altered.
Note that you can also change the half-tone screen information for all pictures in a document
(see 1.7, step 6)
Frequency
is the density of the half-tone screen, measured in lines per inch. Usually a frequency of 100 is suitable for monochrome work and 150 for process colour work.
Check with the bureau/printer if you are in doubt.
speci
es the shape of the half-tone dot. Use the default, u
nless you are experienced in creating PostScript separations
Angle
speci
es the half-tone screen angle for the ink highlighted in the panel above. Unless you are experienced in creating PostScript separations, you should use the default angles as supplied. If the wrong halftone screen angles are set, an undesirable screen clash, called moir
, may occur.
Checking the Separations
At any time you can use the
Separations
menu to view any of the individual separations on-screen.
This menu will help you check that correct number of separations are being printed i.e. there are no additional spot colour plates. Experienced users will be able to use this option to check that the overprint settings are correct.
1.7 Creating a PostScript File
If you are producing full-colour separations, ensure that colour correction is enabled and the correct table is selected.
The standard colour correction table called
TypeSet
should normally be used
. This is con
rmed in the title bar of the
Separations
dialogue box.
You can change the colour correction table using the Colour Choices dialogue box
(see 1.5)
Load a suitable PostScript printer driver and configure it to print to file.
In most situations you should use the PostScript Level 1 driver. Please refer to your computer user guide for details of how to print to a
Choose a suitable PostScript paper size.
The PostScript printer driver provides a wide range of standard paper sizes e.g. A2, A3 and A4. However, printers marks increase the the dimensions of the page, so using these standard sizes may result in your page being cropped.
You should create and use your own paper definition when producing PostScript output for typesetting. Set the paper size to the
Ovation Pro
page size, plus 14mm for the printers marks. The graphics margins should be set to 0. So the paper size for an A4 page should be 224 x 311.
Note that if you do not set a big enough paper size,
Ovation Pro
will warn you when printing. However, to avoid this warning every time you print, you should set up a suitable paper size before printing as described above.
Set the options on the
Print
dialogue box.
Reflect
causes pages to be mirror printed, and should usually be selected if you are printing to film. However, please check with your bureau first. If they require
emulsion side down
Reflec
t should be selected; if they require
emulsion side up
Reflec
t should not be selected.
Choose
Print setup
to expand the
Print
dialogue box to display the advanced setup options.
Centre
should be selected.
Bleed
causes
Ovation Pro
to print an extra 3mm margin around the edge of the page.
If your document contains objects that bleed off the edge of the page, choose the
Bleed
option.
Printers marks
ould be selected. This causes
Ovation Pro
to print the following special marks around the edge of the page
g. 1.9)
Crop marks
show the edges of the page and are used to trim the page to size.
Registration marks
are used to help align the separated film when preparing the printing plates.
Separation names
causes the name of the ink to be printed on each separation. The document name, page number, date and time are printed after the ink name. You can edit this information or add your own text using the
option on the
Screen
dialogue box (see overleaf).
Colour bar
is used to check the quality of the colours on the proofs. Note that the colour bar is not printed on spot separations.
Set options on the Separations dialogue box.
Colour separations
should be selected when you are printing full colour or spot colour separations
g. 1.10)
Plates
menu allows you to choose which separations to print.
All process
prints separations for the four process colours. This is the
default setting.
All spots
prints separations for all spot colours.
Plates
menu also list the four process colours followed by any spot colours that have been de
ned. You can choose to print individual plates by ticking and unticking them directly on the menu.
icon allows you to specify any additional text that is to be printed after the separation name in the top left corner of the page. In addition to ASCII text you can insert macros which will be expanded during printing. The following macros are particularly useful:
lename}
lepath}
{chapternumber}
{pagenumber}
{date}
{time}
{datetime}
The default string is set to:
lename} P{pagenumber}{datetime}
which typically expands to:
Document1
11:41am 27 February 1997
Set options on the Screen dialogue box.
PostScript screen
causes half-tone screen information to be written into the PostScript
le, and should usually be selected
g. 1.11)
Note that t
he options in this dialogue box are intended for experienced users, and should not normally be altered.
Frequency
is the density of the half-tone screen, measured in lines per inch. Usually a frequency of 100 is suitable for monochrome work and 150 for process colour work.
Check with the bureau/printer if you are in doubt.
speci
es the shape of the half-tone dot. Use the default, u
nless you are experienced in creating PostScript separations
Angle
speci
es the half-tone screen angle for the ink highlighted in the panel above. Unless you are experienced in creating PostScript separations, you should use the default angles as supplied. If the wrong halftone screen angles are set, an undesirable screen clash, called moir
, may occur.
Print to the PostScript file.
Once all the above options are set correctly, click on
in the
Print
dialogue box to create the PostScript
When printing the usual
Printing
dialogue box is displayed showing the progress that has been made. the icon in the bottom left-hand corner of this dialogue box shows the the colour of the separation currently being sent to the printer.
1.8 Submitting the File to a Bureau
Most bureaux cannot read Acorn format discs, so your
les must be submitted in PC or Apple format. Please check with the bureau which format they prefer.
PC format discs can be formatted and written to directly from your Acorn system, but make sure that any PostScript
les are given a
le extension.
To format and write to Apple format discs, you need to purchase a separate utility to do this.
For small jobs you will be able to send the PostScript
les using
oppy discs. For bigger jobs you will have to use one of the following alternatives:
Split the job into separate parts so that each part will
t on a
oppy disc
Use a
le archiver such as !SparkFS to compress the
les in Zip format. However, you must ensure that the bureau has suitable software to decompress the
Transfer
les using removable drives such as SyQuest or Zip drives.
Transfer the
les electronically using direct modem connection or perhaps via email.
Commercial Colour Printing
Installation
Litho Printing
Spot-Colour Printing
Full-Colour Printing
Colour Correction
Preparing Your Document
Creating a PostScript File
Submitting the File to a Bureau
This section describes how to prepare
Ovation
documents for
lithographic
(litho) printing. Litho printing is the most widely used printing process today, and is suitable for most applications (except for very short runs of less than, say, 500 copies).
If your document only needs to use two or three basic colours, you can print
it very economically using
spot-
colour printing
. If you want to print using the full range of colours, then you should use
colour printing
Fig. 1.1 - The
Edit colour
dialogue box.
Fig. 1.4 - The cyan plate with knock-out for black text.
Overprint
Fig. 1.3 - The black plate containing the black text.
Overprint
Fig. 1.5 - Correctly printed with no misregistration.
Overprint
Fig. 1.6 - Printed with
misregistration.
Overprint
Overprint
Fig. 1.7 - The
Separations
dialogue box.
Fig. 1.2 - The
Colour
hoices
dialogue box.
Fig. 1.8 - The
Screen
dialogue box.
Fig. 1.9 - Printers marks.
Fig. 1.10 - The
Separations
dialogue box.
Fig. 1.11 - The
Screen
dialogue box.
Image Processing
Chapter 2
2.1 The Process Dialogue Box
Picture
Process
dialogue box
g. 2.1)
is available from the main menu when a picture frame is active. Image processing can only be applied to one picture at a time.
Model
This is the colour model that will be used when you are modifying the picture.
For CMYK pictures,
is the default model
For other pictures
is the default m
You can choose any colour model for any picture, irrespective of the picture type. However note that processing a CMYK picture using the RGB setting will often mix colours between the CMYK plates. This may be highly undesirable.
Colour
This is the colour component that will be modi
The colour map displays a coloured curve for each of the components.
If you choose
, all colour components for that model will be modi
ed in one operation, and the curve of the map is shown in black.
Update
By default the
Update
option is selected, meaning that the picture is updated instantly as changes are made in the
Process
box.
Update
is not selected, the picture is not updated until you click on
. This prevents the picture from being updated after each change you make, which might be quite slow for very large pictures.
Default
Click on
Default
to cancel any processing that has been applied to the picture.
If you have closed the
Process
dialogue box, you can always return to the previous picture settings using the
option.
Use spots
If this is selected any spot colours in ArtWorks files will act as spot colours.
In order to get a spot colour in an ArtWorks file to appear on a spot plate the following conditions must be true.
1. The ArtWorks file must have a spot colour defined in it.
2. The image processing window must have the
Use spots
button selected.
3. The Ovation document must have a spot colour with the same name as the ArtWorks spot colour.
Colour Map
colour map
illustrates the changes made by the brightness, contrast and gamma sliders. Later on in this chapter you
ll see how it can be used to de
ne a custom colour map.
The map shows a picture
s input values on the horizontal axis, plotted against output values on the vertical axis
g. 2.2)
When the the map is a 45
line from 0, 0 to 1, 1, output values equal input values i.e. normal brightness and contrast
g. 2.3)
2.2 Brightness, Contrast & Gamma
You can change the brightness, contrast and gamma values of a picture using the sliders located in the centre of the
Process
dialogue box.
Brightness
Drag the
Brightness
slider to the right to increase brightness, or to the left to decrease brightness. When the slider is in the middle, there is no modi
cation.
Brightness may also be speci
ed by setting a value in the writable icon to the right of the slider. A value of 0 means no modi
cations, -100 means minimum brightness and 100 means maximum brightness.
The colour map illustrates the changes made to the brightness slider. If you increase the brightness, the line on the map moves up and the output values become higher than the input values
g. 2.4)
If you decrease the brightness, the line moves down and the output values become lower than the input values
g. 2.5)
Note that the brightness slider adjusts the levels of colour according to the current colour model, so the description given above is only true for the RGB colour model.
CMYK and HSV Models
With the CMYK model, the brightness slider increases or decreases the levels of Cyan, Magenta, Yellow and Black. So, an increase in levels of CMYK, results in a decrease in brightness. A decrease in levels of CMYK, results in an increase in brightness.
With HSV, the brightness slider increases or decreases the levels of Hue, Saturation and Value. It is not very useful to increase or decrease all three HSV levels simultaneously, but it can be useful adjusting them individually.
Contrast
Drag the
Contrast
slider to the right to increase contrast, or to the left to decrease contrast. When the slider is in the middle, there is no modi
cation.
Contrast may also be speci
ed by setting a value in the writable icon to the right of the slider. A value of 0 means no modi
cations, -100 means minimum contrast and 100 means maximum contrast.
The colour map illustrates the changes made to the contrast slider. If you increase the contrast, the line on the map is rotated anti-clockwise, reducing the range of input values
g. 2.6)
If you decrease the contrast, the line is rotated clockwise, reducing the range of output values
g. 2.7)
Note that the contrast slider adjust the levels of colour according to the current colour model, so the description given above is only true for the RGB colour model.
CMYK and HSV Models
With the CMYK model, the contrast slider increases or decreases the levels of Cyan, Magenta, Yellow and Black. So, an increase in levels of CMYK, results in a decrease in contrast. A decrease in levels of CMYK, results in an increase in contrast.
With HSV, the contrast slider increases or decreases the levels of Hue, Saturation and Value. It is not very useful to increase or decrease all three HSV levels simultaneously, but it can be useful adjusting them individually.
Gamma
g the
Gamma
slider to the right to increase the gamma value, or to the left to the gamma value
. When the slider is in the middle, there is no modi
cation i.e gamma value is 1.
Gamma may also be speci
ed by setting a value in the
range is 0.05 to 5.75, in the
writable icon to the right of the slider. The up/down icons can be used to step through this range in 0.01 increments for values below 1, and 0.05 for values above 1.
The colour map illustrates the changes made to the gamma slider
gs. 2.8 & 2.9)
Note that the gamma slider adjust the levels of colour according to the current colour model.
2.3 Custom Colour Map
You can create custom colour maps using the 4 tools provided
g. 2.10)
Linear
Choose this tool to reset the colour map to a
line from 0, 0 to 1, 1. This sets output values equal to input values i.e. normal brightness and contrast.
Note that the brightness, contrast and gamma sliders are only available when this tool is selected.
Straight Segment
Choose this tool to convert the current map into a series of straight line segments. You can edit the map by dragging the control points. Click Select to add new points, or click Adjust over points to delete them.
Curved Segment
Choose this tool to convert the current map into a series of curved line segments. You can edit the map by dragging the control points. Click Select to add new points, or click Adjust over points to delete them.
Invert
Choose this tool to
ip the colour map upside down. This produces a negative of the curve currently shown on the graph.
Note that you can use the Invert tool to invert the adjustments made by the brightness, contrast and gamma sliders.
2.4 Duotones
Duotone
option allows you to specify the two colours used in a monochrome picture. If the current picture is multi-coloured, it is converted to monochrome
Lower
allows you to specify the new colour for the black component of the monochrome image using the standard colour picker.
Upper
allows you to specify the new colour for the white component of the monochrome image.
Duotone
is particularly useful when commercially printing documents using spot colours. It allows a colour or monochrome picture to be printed using white and any individual spot colour, or even using two spot colours.
De-select
Duotone
to revert back to the original image.
the cur
Image Processing
The Process Dialogue Box
Brightness, Contrast & Gamma
Custom Colour Map
Duotones
Ovation Pro
enables you to modify the appearance of imported bitmap and vector graphics using simple brightness, contrast and gamma sliders
.You can also de
ne custom settings by editing points on the colour map. Any of the three standard colour models may be used to make adjustments.
Ovation Pro
also allows you to change colour pictures into monochrome pictures, and to change the foreground and background colours of monochrome pictures.
Image processing can be applied to Sprites, Draw
les and ArtWorks
les, but JPEG
s under RISC OS 3.60 and later cannot be processed directly and must be converted to sprites