Best file type for offset print, and photoshop editing

[mrbombastik]

Hi,

I have been working on a model that i have not done the modelling part just rendering.

 

1) My first question is that what i am supposed to save the render output for offset print for a catalog. I suppose Tif with 16-bit alpha channel on will be ok.

- Does 8-bit or 16-bit will make obvious difference? And also if i save with 16-bit that i think actually it means 64-bit work, do printing house have to have support for 64 bit? If not will it be unneccessary to save as 16 bit?

-And also what is SGI-LogL options for?

 

2) Secondly, unfortunately some models have some false geometry, overlapping polygon that causes splotches on the white surfaces.

Ok the situation is that; my final render output needs some exposure to be increased and now comes the problem i wonder;

- i have the render and save it in tif format with 16bit and it is rgb indeed.

- i directly open the render output(tif) in ps and perform exposure 1,02.(in rgb mode available as you know)

- the splotches are lightened up (as they are generally in brown color on white surface) and are seen less and i correct the rest with healing brush tool.

- i change the type to cmyk 16 bit save file for print.

 

ok now this healing brush editing and this procedure seems well on the screen but i wonder about the offset print? will that cause any problem.

 

thanks

Edited June 19, 2009 by mrbombastik

[Clanger]

Tiff will be fine just make sure you convert to CMYK and find out the screen res of the print. If it's 180 dpi make your file twice that i.e. 360 dpi. The 16bit won't really make any difference at the print stage but will in Photoshop when you want to adjust the levels, colour etc.

[Matt McDonald]

First and foremost your best bet is to contact the printer and ask them what type of file they want and how they expect it to be converted to CMYK.

 

If the printer is yet to be determined or you are unable to contact the printer here are my tips.

 

TIFF should be fine so long as its not layered and LZW compression is disabled. Don't send them a 16bit image. High bit depth images have not made it into the world of printing. Convert the file to 8bit. There will be plenty of color information in the file and it is unlikely their RIP will be able to handle the high bit depth image. I'd also suggest that you remove the alpha channels, again the RIP probably won't like it.

 

If the RIP can't pass the data that you provided because of the bit depth or alphas you or your client will be paying for another set of proofs once the file has been reprocessed by you or the printer. If you have to pay for it that sucks but if your client has to pay for the perceived quality of your work will take a hit.

 

The CMYK space that you convert to is also important. Ask your printer first but if you can't find that info "Sheetfed Coated" is a good start. It will has a decent but safe color gamut I find it unlikely that an architecture firm is going to go with fancy rendering on a dull, uncoated stock or print enough copies to move away from a cut sheet press.

 

As for your questions about the visibility of your post work. Print it out at its final size and see what it looks like. The press might be a little more forgiving than a good inkjet printer but not a whole lot.