Export CMYK TIFs from X and CX2

[Sean Sedwards]

I've created a plug-in that allows you to export CMYK TIFs from X and CX2 and any other app. that supports PhotoShop compatible plug-ins. You create a 24-bit bitmap copy of your drawing and apply the 'filter' to convert it and save as CMYK. It can use the host application's conversion routine (if available) or its own simple algorithm. Since most host routines are pretty poor, it's my intention to develop the plug-in's ability so that it eventually offers a decent general purpose conversion.

Apart from PhotoShop, which is my reference, Canvas is the only program I tried that could separate to CMYK and hope to reproduce the screen colours accurately. Surprisingly, Xara was next in line, albeit some way behind, followed by Picture Publisher and the plug-in's own routine. CorelDRAW 7 and Painter 5.5 don't provide a host routine, while Fireworks 2 and Paint Shop Pro 5 were buggy in a way that could not be easily overcome. Satori PXL 2.57 and Xara both have bugs that the plug-in fixes. Newer versions of these programs may be better.

Licensing restrictions prevent me from offering LZW compression, however my experiments have shown that zipping an uncompressed CMYK TIF produces a smaller file than either LZW alone or LZW followed by zipping.

This version _works_ and is a way to create CMYK from Xara if you have no other means, however its main function is as a concept prototype. Please experiment with it and post your opinions and suggestions.

Regards - Sean

[Sean Sedwards]

I've created a plug-in that allows you to export CMYK TIFs from X and CX2 and any other app. that supports PhotoShop compatible plug-ins. You create a 24-bit bitmap copy of your drawing and apply the 'filter' to convert it and save as CMYK. It can use the host application's conversion routine (if available) or its own simple algorithm. Since most host routines are pretty poor, it's my intention to develop the plug-in's ability so that it eventually offers a decent general purpose conversion.

Apart from PhotoShop, which is my reference, Canvas is the only program I tried that could separate to CMYK and hope to reproduce the screen colours accurately. Surprisingly, Xara was next in line, albeit some way behind, followed by Picture Publisher and the plug-in's own routine. CorelDRAW 7 and Painter 5.5 don't provide a host routine, while Fireworks 2 and Paint Shop Pro 5 were buggy in a way that could not be easily overcome. Satori PXL 2.57 and Xara both have bugs that the plug-in fixes. Newer versions of these programs may be better.

Licensing restrictions prevent me from offering LZW compression, however my experiments have shown that zipping an uncompressed CMYK TIF produces a smaller file than either LZW alone or LZW followed by zipping.

This version _works_ and is a way to create CMYK from Xara if you have no other means, however its main function is as a concept prototype. Please experiment with it and post your opinions and suggestions.

Regards - Sean

[FLySOLO]

wow cool

i´ve been waiting for this for a long time

now i may be able to choose exact cmyk colors

like the blue (top right) which is 80m 100c

very cool

the bottom black was 100 100 100 100

but reached photoshop as 100k


no further test done

i got to go but more tonight

thanx

FLySOLO

[Wolfgang]

Sean,

this is great, thank you very much !!
Finally it is possible to export black to white gradients as CMYK from Xara !!

If I only would have had that when I made my business cards it would have saved me hours of work !!

Wolfgang

[gwpriester]

I created a sample image, converted it to bitmap, 24-bit. And using Sean's filter exported it twice, with show printer colors enabled and disabled. The image imported into Adobe InDesign 1.5 virtually the same.

I exported the same image from Xara as a TIFF.

InDesign flagged the Xara export as RGB.

What is odd, however, is the two images exported with Sean's plug-in imported at about 1/3 the size of the Xara exported TIFF.

Equally odd, when selecting Sean's plug-in through the Utilities menu (vs right clicking and selecting plug-ins) selecting xPort opens a drop down listing every installed plug-in filer.

Also, Sean, what is the difference between the Host and Plug-in options?

Gary

Gary Priester

Moderator Person

Be It Every So Humble...

[Wolfgang]

Gary,

I don't want to steal the answer from Sean, but I found that "Host" uses the "Xara-Method", meaning the buggy one. Also known as normal Xara X Export.

"Plug-In" uses Sean's method, known as the working one, aka Hooray, finally !!

Wolfgang

[gwpriester]

Thanks for the clarification, Wolfgang.

I tried creating a black to white gradient fill with solid process black and with a registration black and both placed in InDesign.

I opened the file in Photoshop 5.5 and as FlySolo reported the 4-color black showed 100K 0C,M,Y.

The four-color black used in the linear black to white fill in Photoshop was 50% C.M,Y & K.

While I was mulling this over in my mind, I got to wondering if Sean's export recognizes spot colors, so I created a simple set of CMYK squares then added some Pantone spot colors. I exported using Sean's plug in then as a Xara TIFF.

The good news is InDesign read Sean's file as CMYK, the bad news the spot colors were converted to CMYK as well. The Xara TIFF converted all the colors to RGB.

So, I thought, what happens if I export the colors as an Adobe Illustrator EPS file? The image placed in InDesign but the spot colors were converted to CMYK.

Same thing happend with Xara's EPS export, which placed without incident, but no spot colors were reported in the file.

Gary

Gary Priester

Moderator Person

Be It Every So Humble...

[This message was edited by Gary W. Priester on March 24, 2001 at 03:38 PM.]

[Sean Sedwards]

Gary
<blockquote>"1/3 the size..."</blockquote>
Changing the dpi in the plug-in doesn't change the number of pixels, if anything it changes the dimensions, i.e. the number of pixels is defined by the bitmap copy you made but any importing software will interpret the dimensions from the dpi value it finds in the file. By contrast, when you change the export dpi setting in Xara, the dimensions are fixed and the number of pixels changes.

In order to maintain the same dimensions and number of pixels, you must set the plug-in's dpi to whatever you used to create the bitmap copy which, in this case, should also be the same as the value used for the standard Xara TIF export. Most other software automatically passes this value to the plug-in, but sadly not Xara.
<blockquote>4-color black showed 100K 0C,M,Y</blockquote>
The plug-in only sees the RGB bitmap version of the drawing so it's unaware of any spot colours you've used. AFAIK, the only way to get specific CMYK values out of Xara is to export pure vectors as EPS - anything that uses bitmaps (e.g. transparency) will be converted to RGB bitmaps in the EPS file. The only way to output solid spot colours (i.e. those printed on a separate plate using a specific ink colour) is to print to file using a PostScript print driver. Once again, the objects must be pure vector.

The actual colour of CMYK 50%:50%:50%:50% is the same as CMYK 0:0:0:100%, i.e. 100% black, and is represented as RGB 0:0:0. The reason you'd choose one over the other depends on the printing process you're using, but the plug-in sees RGB 0:0:0 in both cases. It seems that Xara has opted for a 'use all plates' method, which is frustrating if your image is greyscale but may have benefits for reproducing colours.

I'll probably have to incorporate more than one 'Plug-in' option to allow for different processes. My primary goal is to create an algorithm that creates a CMYK file that looks like the original when viewed using "Show printer colours" (or PhotoShop's equivalent of Show printer colours).

Regards - Sean

[FLySOLO]

hey sean,

nice work [img]/infopop/emoticons/icon_smile.gif[/img] BUT:

i attached a simple colorchart cmyk lzw tif which you can open and measure the color values in photoshop. most colors are ok but 100 30 20 20 changes to 60 10 0 40. is this in final printed output exacly identical? i doubt it but am not sure.

on the right side is the same thing with a 50% transparency overlayed rect. problem is as you see
100c becomes 50c and 50k. i tried all transp options (darken, mix,...).

if you use the host export options the tranparency darkens the underlying faces BUT with host method color values behave differently.
40k becomes 40 40 40 without any k [img]/infopop/emoticons/icon_frown.gif[/img].

that´s sad

is there hope for cmyk output?

FLySOLO

[Sean Sedwards]

FLy

CMYK 100:30:20:20 and 60:10:0:40 are indeed represented by the same screen colour (RGB 0:50:60) in Xara, however their appearance in print will depend on the process. As I mentioned above, the plug-in only sees the RGB version of the colour and makes its own decision how to convert it into CMYK. The current simple GCR (Grey Component Replacement) algorithm produces a 'Max Black' / minimum total ink separation and makes no compensation for dot gain (the spread of ink droplets) or real ink colours. I'm currently working to improve the algorithm so that (professionally) printed output will look more like the screen image, however Xara's current (and foreseeable) implementation of the plug-in technology does not recognise specific CMYK values used in the drawing. The best solution the plug-in will be able to offer is a choice of algorithms to accommodate different printing processes.

Not surprisingly, adding a 50% black transparency causes the plug-in to add 50% black to the K plate. Any value of C between 50 and 100% will produce the same screen colour in Xara (and many other apps.) but the plug-in chooses the minimum, consistent with its simple philosophy. Xara's in-built algorithm is much more sophisticated (judging by the time it takes) but doesn't use any black at all, as you've said. Viewed in PhotoShop, in this instance I much prefer the plug-in's interpretation, although there is plenty of room for improvement.

CMYK export is always going to be a compromise because CMYK is an output format and Xara's best features (transparency, anti-aliasing etc.) work with RGB derived values.

Regards - Sean