Document class "novel"

Cover Artwork;
CMYK 240% Ink Limit;
PDF/X Compliance

 

Documentation for novel document class

Documentation version: 1.38.

Cover Artwork, CMYK 240% Ink Limit;
PDF/X Compliance

This page serves a limited purpose. It is for the benefit of those who need to submit color print cover artwork in the form of a PDF/X-1a:2001 file, with the artwork as CMYK and 240% ink limit. This is the format required by some American print-on-demand services. It is also generally acceptable to others, whose requirements are less restrictive.

Before you begin: Do you really need to do this? Many print-on-demand services are perfectly happy to accept something such as an ordinary RGB jpeg image, as long as it has the correct size (with bleed area). They can easily process it for print production in a few moments, using professional software. If they do it, then whether or not you are surprised by the resulting colors, will depend on whether or not your original image is within the printer gamut. In other cases, the print service prefers (or insists) that you do the image print production processing yourself. Then, you get to see an emulation of the print colors before you submit the file, and can change your artwork if the resulting colors are disappointing.

The novel document class does not provide any support for creating the original artwork, either image or text. In fact, TeX is not the best way to do that. Use a graphics program (such as the free GIMP) to do your artwork, including text. In the end, your text will be rasterized, just like any background image. For this reason, avoid using small text, and consider using a sans-serif typeface on the cover (even though there is no sans-serif in the book itself).

DO NOT PLACE A BARCODE. If your print service requests a white rectangle where the barcode will go, then include it in your image. Almost every print service is willing to create the barcode from your ISBN, and place the barcode image into your PDF during post-processing. Some of them even demand that they do it themselves. Do-it-yourself barcodes are incompatible with the following instructions.

DISCLAIMER: This documentation, and its accompanying software, is offered AS-IS, WITHOUT WARRANTY EXPRESS OR IMPLIED. USE ONLY AT YOUR OWN RISK. The author is an amateur who does not profess expertise in these matters.

10.1 Begin With PNG

Create your artwork, including all text (but not barcode or barcode text) using whatever means you have. How you do it is not relevant. To follow these instructions, you must provide the artwork as a flattened (no transparency) PNG format image, at correct size (including bleed area) and resolution (dpi).

Example: Suppose your book is 5.5" x 8.5" softcover, a typical size for American fiction. Based on its page count and paper, you are told that the spine width must be 0.62". The required beed width, on all four sides, must be 0.125".

Then, the image is 0.125 + 5.5 + 0.62 + 5.5 + 0.125 = 11.87in wide.

The image is 0.125 + 8.5 + 0.125 = 8.75in high.

At 300dpi resolution (a typical value) the image must be 11.87 x 300 = 3561 picels wide, and 8.75 x 300 = 2625 pixels high. In case of fractional pixels, round upward. The exact pixel count is important.

example rgb image It is best to use the AdobeRGB1998 color workspace, or equivalent. But you can also use sRGB, or equivalent, and in many cases you will not notice much difference. It is helpful to attach (embed) the workspace color profile in your PNG image, especially if it is something other than AdobeRGB1998 or sRGB. Note that the workspace is NOT the color profile of your monitor (if you have it). If you do not attach (embed) the workspace color profile, then remember whether you were using AdobeRGB1998 or sRGB. If you make a mistake here, it is not fatal. It merely means that some colors (particularly bright greens and blue-greens) will print somewhat brighter or duller than you were expecting.

When done, export it as a flattened PNG. An example image of this size can be found in the EXTRAS/novel-coverart-demo folder of the author's GitHub site.

If you are provided with an image other than PNG, you have to convert it to PNG. No alternative. It is easy enough to use GIMP to convert most image formats. If you have a PDF (which is not already in the required format), GIMP can probably open it as an image. Be sure you import it with the correct resolution. Again, the pixel width and height are important.

Cover Text: These instructions assume that your cover text is rasterized, and is part of the image rather than vector text. In many cases your graphics program has enough text capability to do what you need.

If you wish to use TeX to typeset the cover text, do it this way: Use TeX to create one or more PDFs of the cover text, without images. You can create several blocks of text at different pages sizes, if you wish. Open your background artwork in GIMP. Add a new transparent layer above it. Open a text PDF in GIMP. Choose resolution 300dpi, full antialiasing, grayscale or color. The opened text is now a raster image. Copy it, and paste it atop the transparent layer. Anchor it. Use Color: Color to Alpha: white to alpha filter. That removes the white area from the PDF image. Finally, move the text to where it should go. You can rotate the text 90 degrees, but do not resize it! If you would rather the text be at a different size, then either change it in TeX, or use a different resolution when you open the PDF in GIMP. Note that even when you open the PDF at a different resolution, it will still be at 300dpi when you place it over the 300dpi background image; but its size will change.

10.2 Get Some Software

You need the 238% ink limit color profile from Aaron Shepard. This does the magic of ensuring that you comply with the 240% ink limit (the profile provides a little headroom, which seems necessary). It can also be used for softproofing, if you know how to do that. This is not the only possible profile, but it seems to me that it is the best of several available.

You might (or might not) need the Adobe icc profiles (for end users). This link works for Windows or Linux (even though it says "for Windows"). I am told that there is a different link for Mac, but I don't have a Mac.

Get GraphicsMagick or ImageMagick. On Linux, you can install it via your system package manager. On Windows, get GraphicsMagick Q16 binaries for your system (32 or 64 bit) from SourceForge. I am told that versions for Mac are available via homebrew and macports, but again, I do not have a Mac, so I cannot check that. Or, get ImageMagick Q16 for various platforms from here.

10.3 Convert Your Image to CMYK at 240% Ink Limit

example cmyk238 image, back to rgb At right, you can see an emulation of the above cover artwork, softproofed to CMYK at 238% ink limit. It is not the CMYK file itself, but an RGB image that is supposed to help you visualize what happens during conversion. You will notice that the colors are less intense, because the original image contained colors that didn't fit the gamut of the printing process. Colors don't always change; I could have planned ahead, and selected from a palette of colors that fit within the gamut.

Get ready: Make a copy of the above 238% ink limit color profile, and re-name the copy as "238.icc".

I will call your original PNG image "yourimage.png". Put this image, the 238.icc file, and (if necessary) the AdobeRGB1998.icc file in a single working folder.

I will also assume that the image resolution is 300dpi. If it is something else, then modify 300 to the other number, when you see it below.

Step 1: Open a Terminal (Command Prompt) and navigate to that folder.

In the following commands, the initial "gm" calls GraphicsMagick (same code Linux and Windows). If you prefer ImageMagick, then eliminate the initial "gm" on Linux, or change the "gm" to "magick" on Windows.

gm convert yourimage.png embedded.icc

The above command may return the message "No color profile available" and generate a zero-byte embedded.icc file. Not a problem. Discard the zero-byte file. But if it generates a non-zero embedded.icc file, keep it.

Step 2: Next (note the file extensions):

gm convert -strip yourimage.png yourimage-stripped.tif

Step 3: At this point, there are three possibilities:

(a) You have a non-zero embedded.icc file. In this case:

gm convert -profile embedded.icc -profile 238.icc yourimage-stripped.tif yourimage-temp.tif

(b) No embedded.icc, but you know that the artwork was create using AdobeRGB1998 workspace, or equivalent. Then:

gm convert -profile AdobeRGB1998.icc -profile 238.icc yourimage-stripped.tif yourimage-temp.tif

(c) Neither of the above. The image is probably sRGB (default), so:

gm convert -profile 238.icc yourimage-stripped.tif yourimage-temp.tif

Step 4: Now, regardless of which possibility you used above:

gm mogrify -strip yourimage-temp.tif

Step 5: And finally:

gm convert -units PixelsPerInch -density 300 -quality 100 yourimage-temp.tif yourimage-cmyk240.jpg

Step 6: Now verify your work:

gm identify -verbose yourimage-cmyk240.jpg

The report should show that the image is CMYK, that it is at 300 pixels/inch, and that there is NO entry for "Profile-color". It will not have anything to say about ink limit, or SWOP.

10.4 Convert your CMYK Image to PDF/X.

Up to now, you did not need TeX. Now you do. Be sure that you have a working TeX installation, with the novel document class package.

In folder (your TeX root)/doc/lualatex/novel/extras you will find file "novel-cover-template.tex". Place a copy in the same working folder as your image, and modify it as needed.

\SetMediaSize refers to the full size of the image, with units (usually in). This includes the bleed box. For the example image, \SetMediaSize{11.87in}{8.75in}.

\SetTrimSize refers to the trimmed image, without bleed. For the example image, \SetTrimSize{11.62in}{8.5in}.

\SetPDFX[CGATSTR001]{X-1a:2001} will get you "Us Web Coated SWOP v2" output intent (most common the USA), and PDF/X-1a:2001 compliance. The Output Intent *.icc color profile will NOT be embedded, because this is almost always the way that print services want it. The PDF contains a code identifying the intent, so there is no need to embed the color profile (and disadvantages to embedding it). In the unlikely event that they demand the Output Intent color profile embedded, put an asterisk on the command.

For compliance you need to use \SetTitle. The title for this file might not be the title of your book, because this file isn't your book. Ask you print service what they want. Same with \SetAuthor.

You can use \SetApplication and \SetProducer to change internal identifiers. Don't use these unless you have a reason.

\SetCoverImage is self-explanatory. Must have file extension jpg, jpeg, JPG, or JPEG. Must be CMYK. Note that TeX cannot verify whether the image is in correct color space. It will compile, even if the image is wrong. Beware!

Do not attempt to write anything between \begin{document} and \end{document}. If you erroneously put some text there, the document will probably compile, and it may even be a valid PDF/X file. However, the resulting text color will almost surely be wrong. If so, the problem will be detected when you submit your file (wrong ink limit or color space). However, this is not a fundamental limit. It is possible to place TeX text over the image, but this documentation (as of version 1.32) does not show you how to do that.

Compiling may take a little longer than expected. If your TeX system opens a PDF viewer automatically, the image might be missing (or partial) until a few seconds after the viewer opens. Be patient. The file size is large.

10.5 Final Check

Open the PDF in Adobe Reader, which does a trick that no other free software will do, to my knowledge. If your platform does not have Adobe Reader, then find a friend who has it. May be a different platform.

In Adobe Reader, go to Edit, Preferences, Documents. Check "Save As optimizes for fast web view." Then go to Edit, Preferences, Page Display. Check "Show art, trim, and bleed boxes." Then OK.

Open your PDF. You should see a light green box, just inside the image boundary. This shows the Trim Area. This box does not print; it is only for visualization. Go to File, Properties, Fonts. There should be no fonts listed.

Then, "Save As" the same file name (or another one, if you prefer). This will optimize the file. You probably do not need to do that, but it does not hurt, and a few services expect it.

There will always be some difference between color as viewed on your monitor, and color as printed. This is due to the difference between emitted light (your monitor) and reflected light (print). In professional use, the monitor will be calibrated, and operated at a specific screen brightness. The print will be viewed under lighting with a specific color temperature and illumination. Your own colors are not that critical, are they? If you have a calibrated monitor, and view the PDF and images in color-managed software, then what you see on your computer will be reasonably close to what prints. If your monitor is not calibrated, or you are not using color-managed software, then the printed cover may have its greens a bit more colorful than you were expecting. That doesn't mean there will be a greenish cast. It merely means that things such as spring leaves and shamrocks will be a bit greener (in print) than you expected.

Remember the Disclaimer! Your PDF file should now be ready for submission. Only "should," not "is," because this documentation and its accompanying software comes without warranty. Submit at your own risk!

All I can say is that it "works for me." Screenshot from Adobe Acrobat Pro:

works for me

10.A Appendix: The 240% Ink Limit Color Gamut

240% gamut samples At right are color samples in the HSV color coordinate system (as used in color picker for GIMP 2.8 software). Each sample would normally be a rectangle, with lightness as horizontal axis, and saturation as vertical axis. Note that "saturation" is a technical term, not to be confused with "chroma (colorfulness). The highest chroma would be at upper right of each rectangle. There are 36 hues, corresponding to 10 degree increments on the HSV color wheel.

A portion of each rectangle has been whited-out. Those colors are inaccessible to the SWOP CMYK printing process with 240% ink limit. Most of the inacessible colors are at the upper left of each rectangle, where the combination of low lightness and high saturation would call for too much ink. In a few cases, the inacessible colors simply cannot be reached by standard CMYK inks.

In general, the range of color that can be accurately portrayed on a consumer-grade laptop monitor is smaller than the range that can be printed. So, in the above image, your monitor is faking many of the colors, by showing them as closely as it can. The method of faking may depend on your computer, and on your browser. In many cases, nearby colors are also faked, so that the color error is not all in one place.

240% gamut with monitor limit At right, the colors that are probably faked by your monitor have also been whited out. These tend to be in the upper portions, where the colors are too chromatic for inexpensive LCD technology. Expensive professional monitors could show more. If you look back at the first image, you will see that the faked areas seem to be in a uniform color, because your monitor cannot display the differences.

If your cover artwork uses colors from the first image, then those RGB values can be reasonably well converted to printable CMYK at 240% ink limit. What you'll be missing are richly colored shadows.

If you limit your cover artwork to colors in the second image, then you are much less likely to be surprised by overly colorful areas in print, which couldn't be seen that way on your monitor. On the other hand, maybe you would like to use all of the colors available in the first image, with the understanding that the printed color will be a bit surprising. It's up to you.

You may have heard that when artwork is converted to CMYK 240%, colors tend to be "duller." Not necessarily. The second image looks much duller than the first, but that is because large areas of identically-faked color have been whited out. Those colors are still in the second image, but they only occupy a thin boundary of the remaining color.

The full-size color sample images are in docs folder extras, and are named SWOP240gamutHSV.png and SWOP240gamutHSV-monitorlimit.png.