Have any LARGE scale printing suggestions??

12/13/2005 07:05:52 PM · #1

What are your suggestions for creating high quality large scale prints (18" X 12" or larger)?

I've spent a lot of time lately preparing larger prints for display. A workflow evolved from that process I will share. I'm curious about your experiences making large prints and what you do to make high quality prints.

Assumed starting point:
This workflow starts with a fully post processed but uncropped and unsharpened image saved in its original form as 72dpi but in .tif format in the Adobe RGB (1998) color space. The idea is to retain as much color information as possible for as long as possible in a standard lossless and editable format. Images are not sharpened because the amount of sharpening necessary depends on the size and dpi (dot per inch) of the final output.

Lets say that you want to make a 20" X 16" sized print at 300 dpi.

Issues:
1-For most cameras this print is about 4 times larger than the camera's actual output and therefore will have to be scaled up to the larger print size.

2-Image defects that are almost impossible to see during normal post processing for a web image become glaring defects in large print sizes.

3-Image noise, haloing and color banding in soft focused backgrounds are the main image defects that appear when creating large print files.

4-Final image sharpening becomes problematic because you have to account for proper viewing distance and that is hard to estimate on screen.

This workflow addresses those issues:

Workflow:

A-Review and correct the original post processed file:

1-Review the post processed file under the microscope at 300-500% scale and correct noise and haloing defects. This allows you to see the image close to the scale it will be printed at. Because your monitor only displays 72 dpi or so the image will look HUGE compared to the actual size it is printed. Don't be fooled into thinking you do not need to review it at those sizes, you do.

2-Apply additional noise reduction if needed then use the clone, healing and/or blur and smudge tools as necessary to clean up remaining noise, color noise and trim unsightly haloing. This is a time consuming task. Some images will require more work than others.

3-Save the "fine adjusted" post processed file.

Now you are ready to go on to create a master print file. Since prints may have many different aspects I create one large master print file for the whole image and use that as a source for all prints at all aspects. This makes it easy and fast to crop and print later.

B-Create a master print file:

4-Flatten the image and save under a different name. (I append prt to the image file name to show it is a print file. ex. DSC03215.tif is saved as DSC03215prt.tif

5-Convert from 8-bit to 16-bit color. (This helps minimize defects that appear in the upscaled image)

6-Apply YOUR image resizing methodology. CS2 has one or you might apply one of the fractal or step interpolation purchased products to scale up the image at small increments for a better quality larger print file. (I use Fred Miranda's scale interpolator)

In my case the full scale master print file from original image is upscaled to 24" X 18" at 300dpi. That is a big, big file.

7-Perform another review and correction to the upscaled image. Basically you are repeating step 2 because other fine detail defects will be introduced or become more apparent in the full sized print file. This will be reviewed at 100-200% actual size. This appears SUPER huge and you will finding yourself constantly reducing and enlarging during the process to better see the overall effects of your corrections! :)

8-Apply USM as needed. It takes practice to figure USM based on how far away from the print a person would normally view it. Large commercial print shops often introduce fine-grained noise into the print to improve how it looks from the proper viewing distance. You might want to experiment with that as well.

9-Convert back to 8-bit and save the master print file.

The 8-bit/16-bit conversion before upscaling the image to full size reduces color banding that can be introduced or brought out by PS into soft focused areas during the upscale process.

There are two reasons for converting back to 8-bit before saving. One is that most commercial printers require 8-bit images and the other is it reduces the master print file's physical size by 1/2. A 16-bit print file scaled to 24" X 18" at 300dpi can be 500 megabytes or larger!

C-Actual printing:

10-Open the master print file.

11-Select the print aspect you want and crop the image.

12-Turn off "Resample Image" and scale to the actual physical size (16" X 20", 12" X 18", etc) you want. Unless you are cropping a very small portion of the image or printing at a very large size (like 10" X 30") your printed file will actually be greater than 300dpi if the original was upscaled to around 24" X 18".

13-Print the image for the proper printer/paper combination... or

14-Save file for a commercial print shop.
Convert output profile from Adobe RGB (1998) to sRGB, change proof profile to sRGB so you can see how it will be printed and then "save as" a .jpg file for output for a commercial printer. If you know what printer and paper it will be printed on and you have a profile for it then review with that proof setup for a more accurate view of how it will look when printed. Most print shops, like DPCPrints, requires sRGB and .jpg output. Often, like DPCPrints, your output file cannot exceed a maximum size like 16 megabytes.

Canon EF 16-35mm f/2.8L USM

12/13/2005 08:22:31 PM · #2

OK... OK... don't everyone jump in with their ideas to fast...

We don't want to drag down the bandwidth and deny other DPCers access to the site. :)

oOWonderBreadOo

Canon EOS-5D

12/13/2005 08:33:35 PM · #3

well... 72 dpi? how about that for your first question. :0)

I usually go from RAW to 300 tiff. Why is 72 better (or is it?)

Canon EF 100-400mm f/4.5-5.6L IS

12/14/2005 02:29:14 PM · #4

Originally posted by oOWonderBreadOo:

well... 72 dpi? how about that for your first question. :0)

I usually go from RAW to 300 tiff. Why is 72 better (or is it?)

Interesting question... My answer: I don't know. That is just the way I've always done it.

Sounds like you are saying that you save your original image as a 300dpi .tif file and then perform all your post processing on it. Is that correct?

What do other DPCers think?
Should you perform all post processing on a 300dpi files or do post processing on 72dpi images and later convert them to 300dpi for printing?

I would like to know the pros and cons of both approaches.

DjFenzl

12/14/2005 02:33:46 PM · #5

I could be wrong but I don't think DPI makes any difference when you are editing the picture (unless you resample it)

My understanding is 72DPI is standard screen resolution for images. 150DPI for newspaper print and 300DPI for magazines.

I don't think it matters when you convert it.

jefalk

Canon EOS-1Ds Mark II

12/14/2005 02:38:45 PM · #6

The quick basic answer to the 72 is better thing is just as basic actually. In reality the digial images are all in the end 72dpi. From the pro lab prints too the simplest point and shoots. At the end of the day its all adopted too 72dpi.

Getting too the end of the day is a 4 year degree these days however!

But, too your end result - the quality at the image capute is king in all cases, no question, no discussion - and in every way. All the way from the scene through the glass and onto the sensor.

Just the way it is...

John

12/14/2005 03:13:33 PM · #7

Dan... Since 72dpi is standard PC screen resolution does it make sense to post process at screen resolution? I honestly don't know the answer.

John... I could be wrong but disagree that print shops adopt large prints to 72dpi. (I do agree they can only be viewed on a screen at 72dpi) The whole purpose of incrementally resampling an image to a larger print size (I'm talking 12" X 18" or larger) is to add data to the image to retain the original quality of photograph in the large printed form. That is why DPCPrints and other commercial print shops that have a quality standard require a minimum of 150dpi for prints at the size they will be printed. That prevents jagged digital pixel boxes from showing up.

Message edited by author 2005-12-14 15:14:18.

DjFenzl

12/14/2005 03:34:18 PM · #8

Originally posted by stdavidson:

Dan... Since 72dpi is standard PC screen resolution does it make sense to post process at screen resolution? I honestly don't know the answer.

I don't think changing DPI while you are editing the picture will make any difference (without resampling) because your screen resolution remains constant and DPI is more of a ratio when it comes to your computer. For example if you have a 75DPI image and it's 8X10 if you convert it to 150DPI the image will be 4X5 - but on screen it will be exactly the same, it will only print different.

In other words, you can't see the image at 300DPI on your monitor (you only are changing it for the printers sake) so setting it to that to post process won't make any difference in what you see on the monitor.