Subversion Repositories Scribus

Rev

Rev 594 | Rev 3295 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
594 cbradney 1
<qt>
2
<title>Notes on Importing Issues with Scribus</title>
559 cbradney 3
<h2>Notes on Importing Issues with Scribus</h2>
4
<p>Although Scribus imports most common DTP image formats like TIFF and EPS, over time one of the more difficult tasks in DTP is getting stuff into your layout. Unlike some other DTP programs where printing can be finicky, Scribus print and PDF export has always been very reliable. I can think of
5
a handful of times when I had crashes or could not get the desired print or PDF from Scribus. With correctly prepared images and files the output from Scribus matches proprietary layout programs.</p>
6
<p>In my experience, the keys to this are using the right format for the right type of image. Whenever possible, import your images as vector via SVG, EPS or PDF. The other is I am <strong>really</strong> picky about fonts. You will see this noted through the docs; when you are working with high-end DTP tools like Scribus, font quality matters. In professional DTP, it matters <strong>a lot</strong>. Probably the number one reason postscript output fails, whether to a printer or PDF export, is a dodgy or corrupted font.</p>
7
 
8
<h3>TIFF, JPEG, PNG what is the difference?</h3>
9
<p>Hints (or) avoiding some issues which can baffle a beginner:</p>
10
 
11
<h3>If it looks good on screen it will look good on paper</h3>
12
<p>Nope, sorry. One of the most common beginner mistakes is to assume a nice looking JPEG from website will print nicely on paper. Most websites use JPEGs, gifs or sadly, less commonly, PNGs. JPEGs, by their design, are lossy compression. In the process of compressing a JPEG, data is discarded and permanently lost. Moreover, there is a type of JPEG called progressive which is pure poison in a postscript work-flow. A progressive JPEG is the type that partially displays as it is downloading in a web browser. <strong>Avoid these at all costs.</strong> Lastly, remember, most web page graphics have a resolution of 72-96 DPI. Scribus can generate PDFs with 4000 dpi.</p>
13
<p>For high-level postscript printing there are three kinds of file formats that work well for images like photos and anything that is made up of pixels and have been time tested: TIFF, tif and Tiff.</p>
14
<p>No matter which way you spell it, a Tagged Image File Format is the file format for bitmap images. Period. End of story. Don't give me any arguments: I'll win.</p>
15
 
16
<h3>Why?</h3>
17
<ol>
18
        <li>It is a &#034;lossless&#034; format. The compression scheme does not reduce quality.</li>
19
        <li>For your purpose of working with Scribus, the GIMP does a fine job of exporting or saving them from the native XCF format.</li>
20
        <li>It handles ICC profiles without problems. You can &#034;tag&#034; it with the little cms utility tifficc or embed an ICC profile in Photoshop, Photopaint and other bitmap editors.</li>
21
        <li>It supports CMYK colors better than almost any other bitmap format.</li>
22
        <li>Every high end DTP application can support them, including Scribus.</li>
23
        <li>TIFF files, if they are prepared properly in the GIMP or Photoshop are extremely reliable when printed commercially and rarely do postscript devices have problems with them.</li>
24
</ol>
25
 
26
<h3>Caveats</h3>
27
<p>There are more than fifty different flavors of TIFF. Not every image editor saves them with the same fidelity to the standards. GIMP through its use of libtiff, shared with Scribus, does a fine job of supporting Tiffs. The way I work with files from GIMP is to save the original file in the native GIMP xcf format and then, once edited to your satisfaction, re-save as a tiff or with screen shots meant for the web, PNG.</p>
28
<p>Now the exception to that rule is PNG, especially for application screen shots. PNG has a lot of advanced features, like ICC color support and real alpha transparency, which are often not supported well by some applications (a certain leading browser comes to mind). PNG also compresses very well. The only time I prefer Jpeg to PNG is for photos with high dynamic range, mostly for reasons of size on a web page. For creating PDFs with screen shots, PNG is superb and will print well, as long as you do not make any scaling adjustments which reduce the image size. So if you have a screen shot which is typically at 72-96dpi, but you need to shrink it, do so by scaling the image in the GIMP or within Scribus. Whenever you are scaling screen shots disable re-sampling in any image editor. With screen-shots you should never reduce the number of pixels or you will lose sharpness quickly.</p>
29
 
30
<h3>If it looks bad on screen, it will print terribly</h3>
31
<p>EPS files or Encapsulated Postscript files. EPS files natively have no screen preview at all. EPS files are really a special subset of postscript instructions. They typically look just plain awful on screen if they have a TIFF or PICT preview embedded or are just a simple gray box. EPS have two important virtues: They print well to both high resolution printers or when creating PDFs. EPS files can be resolution independent and are the only file you can (sometimes) safely scale larger than 100% than its native size without degrading image sharpness.</p>
32
<p>The one issue you might find with EPS files is while a lot of applications can generate EPS files, not all do so with the same fidelity to high-quality printing, nor do all apps follow the EPS specs properly. One way to test an EPS for use with Scribus, is to open the EPS in GSview and look in the message box, by pressing Shift M. This will show the output messages from Ghostscript. Ghostscript is correctly quite fussy about EPS files. So, if you are trying to import EPS files and they do not work properly in Scribus and GSview/Ghostscript is spitting lots of error messages, try using a different application to generate them.</p>
33
<p>One reason for the ubiquity of EPS files in DTP is there is another DTP application which historically had poor support for TIFF and other bitmap image files, but does have good support for EPS import. So, many DTP users habitually create EPS files from bitmap images from Photoshop or others. Unfortunately, this can have the side effect of receiving image files which may need adjustment, but without the original image file - impossible. EPS is ideal for receiving vector artwork like maps, mixed with text. The caveat is the fonts should be embedded in the EPS properly
34
to print properly from Scribus.</p>
35
<p>Fortunately, Scribus automatically creates a low resolution preview image which is handy for placing and adjusting sizing on the page. When importing an EPS, Scribus generates a 72dpi PNG preview of the EPS, so do not be concerned if it does not look sharp right away. Printing or exporting a PDF will generate the high resolution image in the file.</p>
36
<p>Skeptical about the difference between a vector and a bitmap image file ? Here is an example that you can see for yourself. Go to: <a href="http://www.isc.tamu.edu/~lewing/linux">http://www.isc.tamu.edu/~lewing/linux</a></p>
37
<p>Get the linked postscript, which is an EPS version of Tux and then right click and download one of the gifs. They are about the same in file size. Now create a new doc in Scribus with 2 regular size pages. Place the gif on one page and then the eps file on another. Export a PDF at 600+dpi.
38
Open in Acro Reader. Zoom in 200-400 %. Now you see the difference...</p>
39
<p>Why the difference? Scribus creates and Acrobat Reader renders something called postscript operators - another fancy name for using math in drawing curves on screen and when printed. A gif, or JPEG is just a bunch of pixels, literally dots to create the image.</p>
40
 
41
<h3>My New Favorite File Format</h3>
42
<p>With the recent addition of SVG import, this gives users one more excellent way of importing images and artwork. SVG - Scalable Vector Graphics. Scalable is great because well it is scalable, meaning you can in theory enlarge the the graphic to the size of the side of a house and it would retain its sharpness. Vector is how it does it, vectors meaning the shapes are drawn by mathematical commands to greatly simplify. More on the next page on some neat importing tricks.</p>
43
 
44
<h3>Think About Fonts When Importing Too</h3>
696 cbradney 45
<p>A similar issue is the fonts look good on screen, but do not print well. Usually, this is the case of freeware TrueType fonts, downloaded from the web. TrueType fonts, on average will look better on screen, but may not print with the intended results. However, it takes a huge amount of time and QA to create high-quality fonts, especially correctly hinting TrueType fonts. Notice that there are very few high-quality fonts which have been developed in open source. There are a few, but sadly not with the regularity which we see new apps pop up on Freshmeat.</p>
559 cbradney 46
<p>Conversely, the Type 1 fonts included with Ghostscript are not optimized for on-screen appearance, but they usually make excellent printer fonts. The fonts actually were made by URW++, a well regarded type foundry and were donated to the Ghostscript distribution by Artifex. The only issue is when the Nimbus fonts - their true postscript name are often aliased to Times, Helvetica and Courier. This results in a user thinking it is not necessary to embed these fonts as they come standard with Acrobat Reader. Unfortunately, if they are not embedded Acro Reader does a particularly
47
poor job of emulating these with its built-in multi-master fonts. With Scribus, you will not have this worry, as Scribus uses the correct Postscript name embedded in the font.</p>
594 cbradney 48
<p>The Bitstream fonts included with Xfree86 like Charter and the new Vera fonts are fine fonts for printing. I also like the Utopia family which is actually an Adobe Type 1 font donated by IBM. When creating Scribus docs in PDF form, I pretty much use this family exclusively.</p>
49
</qt>