Mike Chaney's Tech Corner

I want to send images to an online print service using Qimage's Print To File feature.
AFTER resizing in Qi Ultimate, I want to add a frame in my photo editor, PhotoLine.
The paper sizes are from 500 x 700 mm to 700 x 1000 mm. The service uses Epson printers, 9600 amongst others.

I have fiddled around in Qi and got confused. In Mikes article "Wide Load: Tips for Printing LARGE",
 http://ddisoftware.com/tech/articles/february-2006-wide-load-tips-for-printing-large/msg25/#msg25
chapter "Understanding software differences WRT sizing",

I am relieved to read

"In Qimage, you will be told that the print size is larger than one page and will be asked if you want a poster. If you say no, you'll end up with a 15.766 x 19.333 inch print (same size as PhotoShop) but without the edges cropped off."

This is what I want. It does not matter that the image is slightly resized, but it must not be cropped, and it must not have a margin. So how do I achieve this?

The following settings seem to work, but I'd appreciate if you could confirm, and I have some questions.

As an example, I have chosen an image which is 480.0 x 665.3 mm, to be printed to a 500 x 700 mm sheet.
(The 480 measure is chosen, the 656.3 is obtained by resizing in my editor with Lanczos 3, just to try out.)

Here are the settings I tried:

File/Print to/File:
Page width: 480 mm, Page height: 665.3 mm, Resolution 240 PPI.

DEFAULT Print Properties: (Print Properties accessed via the button at bottom right under the preview image).
Here I don't know if I am to select B or B+. I have read the popups, but don't really understand what they mean. I think what confuses me is that I am not sure how "print" size relates to (net) image size on the one hand and to paper size on the other. Anyway, I have set Borders to 0. Also I see that choosing "add borders" or not in Properties/Custom/Specific SIZE changes this setting automatically backwards, so to speak.

Special Sizes FIT to page: Auto Cropping OFF.
Special Sizes BORDERLESS:
Here, Auto Cropping can not be turned off, which confuses me.
When I go back to FIT, it looks like I left it, Auto crop OFF. But if I click OK, THEN go back to FIT, Auto Crop is turned ON.

Then, in the Print Properties for the INDIVIDUAL image, (accessed via the button inside the image; however, this opens the same dialog):
Print Properties/Custom/Special Sizes/Enter specific SIZE: 480 x 665.3
I chose not to add borders, but wonder if it makes any difference with borders set to 0.

Result:

Now, the info on top of the preview image says Page: 479.9 x 665.2 mm
The mouse pointer hovering over the image itself says 480 x 665.3 mm - success!
So this is what Mike writes, the image slightly larger than the page.
Opened in my editor, the image does not look cropped - can I be sure that it is not?

Another question concerning print resolution in Job Properties: Help, Example 1, §2, says that the first of the 2 resolution values should be set to Max, the second to High - why not both to Max? This is also what is recommended in the table at the end of Mike's article quoted above.

Also in Job properties: Printer ICC: My print service has advised me to use a standard profile (ProPhoto in my case), NOT their paper profile. The Help example 1 §3 however says OFF. ?.

Thank you for any help!
Hening.

Hening,
you are getting confused with printing on paper and printing to file regarding spreading print over more than one page and borderless. The latter is a driver setting, not related to PTF
First forget about an image having a size in mm. In reality it doesn't, it has a size in pixels. Secondly, Qimage works by you specifying the finished print dimensions in mm or inches. All the interpolation and re-sizing is taken care of - that's what it does. Interpolate only once - in QU!
Next think about aspect ratios of image & print size/paper.
You say 480 x 656.3mm at 240ppi so pixel size is 4535 x 6201 (ignored decimals as pixels must be whole numbers).
Thus the aspect ratio is 6201/435 = 1.367.
However you are talking about printing on 500 x 700 paper, its aspect ratio is 1.4 and thus there is small mis-match. With crop scissors off that will mean white space; on will mean some cropping.
Adding borders will change the aspect ratio a little.

I suggest this procedure.
Add your frame in your editor but make sure the finished aspect ratio matches that of the paper if you want it to fill it completely.
Qimage: set print to file with a paper size of 500x700mm and a resolution as specified by the printing company. You mentioned 240ppi, but 360ppi would be better for an Epson printer, or if set for finest detail 720ppi.
In the PTF dialogue, put the dot in "Printer, use Printer ICC". OK
Back on the main screen, job properties set the printer ICC to whatever you want embedded in the image. QU Colour Management/Images  preferences must be set to embed profiles.
Set Interpolation to Fusion (the best).
Set print sharpening, start off with default 5, see how that goes.
Add the image to the queue set as "Fit to Page"; crop scissors on or off should not make any difference if all the numbers are correct.
If you want to add a border in QU, use "B", ie. the print size remains the same as specified and not increased by the border.
Click print to create a new image.
I think I've got all of that correct but see Learn by Example 25a is the correct Help on preparing images to send to a printing service.

Terry

Hi Terry,

thank you for your fast reply.

I leads me to new questions, and some clarification I may need to do.

Concerning the procedure:
I think the print service will print on rolls. He just advised me to supply 1 file per image, so this 500x700 was just to give a rough idea of the sizes I'm talking about.
(This is the paper size I will have to pay for.) Also they will cut the image in the end, so I need not worry about that. I only want to avoid any cropping or adding unwanted stripes before I add the frame.

Adding the frame before resizing will not work for me. The width of the frame is calculated WRT to the final size, and so is the size of a little text inside the outer black frame. I will not adjust the frame to fill the paper size. The frame is part of the image in the sense that its proportions should be as I want them.

So I think if my above procedure is in fact correct and giving me a non-cropped image, I will stick to that. In the end it is more important that it works as intended than that I understand it…

I have now set 720 ppi in the PTF dialog, and it is reflected in Edit/Prefs/Printing Options and on top of the image preview. But the mouse hovering over the image still shows 240 ppi - ??

On 2 images, my above procedure seems to have worked. On a third, there is a little  problem. In Print Properties/Special Sizes, I entered 757.3 x 569 mm. On top of the Page Preview, it says 757.3 x568.9. So one direction is reduced, the other not. I guess it has something to do with mm and whole pixels. Will it produce a narrow white stripe on the one side? 0.1 m does not sound much, but my frame contains an inner light-gray edge which is just 3 pixels wide, which then would be widened by 1/3rd  on one side only (at 240 dpi, where 1 pixel is about 0.1 mm).

Then a question that has actually nothing to do with procedure or understanding Qi in particular, but print scaling in general.

I thought like this: There are 2 ways of resizing an image: changing the printing resolution, or interpolating the image. And I thought that changing the printing resolution was less damaging to the image than interpolating. Hence, since I want to enlarge the image, I set the lowest acceptable resolution. Now I understand on you that I should print at the printers native resolution regardless that this would require heavier interpolation. Correct?

Regardless which resolution I end up choosing: Why not the same for print and poster? Is a "poster" in Qi (in Job Properties) defined as stretching over the edge of a given paper size, or just as a print above a certain size? For 1 given image, what relevance has it to specify 2 (different?) resolutions? In other words: If I specify 2 different solutions, which one will Qi choose for a given image?

Thanks again for your help. Hening.

Hi Hening,
That is fine, just make sure the size specified in the Print to File Dialogue has the same proportions as the image.
Just checked, I see what you mean. The data you see there is only for printing on paper I think and would be the print resolution for that situation. But remember, Q interpolates to the printer native resolution up or down.
Eg. If your PTF page is 700 mm wide and you specify 720ppi, the width of the image will be ((700)/25.4) x 720 = 19842 pixels. Your PTF image should be similar depending on the actual size you choose as the "page" size.
I just checked out an example here and got a similar small discrepancy. I eliminated it by checking the PTF size in the Queue tab (the page size above the preview was the same value too) and then entered that value in the PTF dialogue as the page size. You would get a white sliver otherwise. But in reality, if your printing service is cutting & trimming from a roll, wouldn't they trim that off?

Qimage works by interpolating to the printer native resolution or if PTF, whatever you specify.
I'm not sure what you mean here?
If you are printing on paper, Qimage determines what the native resolution of the printer is from the driver - it can vary according to the driver print quality setting. EG. Epson finest detail 720ppi but a lower setting may be 360ppi.
The whole purpose of this is to prevent the driver doing any interpolation at all; their interpolation algorithms are far inferior to what Qimage does. If you print requires a large amount of interpolation, then Qimage will do the best possible job to achieve the print size required from the image pixel size that exists.
When you print to file for someone else to print, you have less control of the process. You really need to know in detail what machine settings the external printer is using.
A local Epson repair company near to me has a large format printer for customer's prints; they use Qimage. What a good idea: you just give then you image file as it is from your editor, and they print at the mm or inch size you require.They let Qimage do the work  8)
A poster print usually means a print spread over several separate pages that can be assembled into one large print.
I suppose it can mean any very large print where the viewing distance is also large. This means the print resolution need not be as fine as for smaller prints because a viewer would not see the detail at those larger distances.
We need the input of an experienced Q user for large prints here!
Again, not sure what you mean here. Qimage chooses (normally) the native resolution of the printer from the driver setting. The poster options are a whole number fraction of that maximum value. You decide what is needed in that case. Lower resolutions will speed up the processing, especially noticeable for large prints.
Terry

Hi Terry

>> But the mouse hovering over the image still shows 240 ppi

I have now loaded a new copy of the same image, after having set Qi to 720 ppi, and now, the mouse hovering over the image says 116 ppi, a lower value, as exspected.

The 0.1 mm white sliver on the 757.3 x 569 mm image:

>I eliminated it by checking the PTF size in the Queue tab (the page size above the preview was the same value too) and then entered that value in the PTF dialogue as the page size. You would get a white sliver otherwise.

I understood this in the way that you entered the reduced size in the PTF dialog? in this case 757.2 mm

I did that and got a message "The new page size is too small for some of the prints in the queue. All prints larger than 1 page will be resized to fit on the page."
 
and now the display is as follows:
Top of preview dialog:    757.2 x 568.9 mm (720 x720)
Print Queue dialog:       757.2 x 590 mm
Mouse over image:       752.2 x 569.0

So the page has been reduced, but so has the image, and the sliver will still be there. And the print service can not cut it off: it will be between "net" image and frame.

The 2 images where everything seemed to work were in portrait orientation, whereas this one is in landscape. Could it have something to do with this?

>>And I thought that changing the printing resolution was less damaging to the image than interpolating
>I'm not sure what you mean here?

On the monitor, If I set resolution to 240 ppi, I get an image of a certain size if viewed at say 100%. If I decrease resolution to 96 ppi and still view at 100%, the image is much larger. So here I can increase image size without interpolating - i.e making up new pixels which are not real, as I understand it, and which I associate with reduced image quality. But obviously, I miss something here.

>>If I specify 2 different solutions, which one will Qi choose for a given image?
>Again, not sure what you mean here.

I have loaded 1 image. In Job Properties, there are 2 Resolution fields. If I enter 2 different values, which one will Qi choose for this one image? I think it must choose Poster only for the cases where Poster is specified by extending over the paper border.

> Qimage chooses (normally) the native resolution of the printer from the driver setting.

So I must check with the service to get the driver setting. If he does not do it on beforehand, I hope I can talk him into using Finest Detail and 720 dpi.

Puh this is complicated!
Thanks again for your help. Hening.

You could calculate the PTF page size accurately using the whole number of pixels and use that. Although the dialogue shows only 1 decimal place, it will accept at least 2 places.
Alternatively, go back to the original page size and put crop scissors on to eliminate and white space. This will crop the image a tiny amount which you may be able to live with.
Terry

> You could calculate the PTF page size accurately using the whole number of pixels and use that.

I tried to do this.
To calculate the exact size, I faked resizing in my editor (on a dup of the image). Setting 720 dpi and the short side to 480 mm, the pixel count became 18,111 * 13,606 = 638.9 * 480.0 mm.

I entered these mm values into Qi in the PTF dialog and in Print Properties/Custom/Enter specific SIZE, and clicked BORDERLESS.  I got the exspected "Is-too-large"-dialog. As the result, Qi displays the following:

Top of image preview:    638.9 x 479.9 mm
Print Queue:            637.7 x 480.0
Mouse over image:      637.7 x 480.0, 137 dpi

Something must be wrong. On the long side, the page is larger than the image (by as much as 1.2 mm), on the short side the page is 0.1 mm smaller than the image, as exspected. This can not be a matter of the second post-comma digit.

The image is displayed correctly in landscape orientation.

??? Hening.

The image, treated by Qi, then re-opened in my editor and displayed at 720 ppi, shows no sliver and no cropping, and is displayed as having the exact same pixel count and metric dimensions which I entered in Qi.

So it may look like Qi does the right thing - but just the display is confusing. This is however bad enough, because how would I know.

Still worried - Hening.

I'm not sure why, the only thing I can think of the monitor resolution is too course to show the small differences.
If you had put the new image in the Qimage queue with the same page size and hovered the mouse over the preview, that too would show 720ppi  :)
One other tip, when playing with those small (or large) differences in the page size, you should really go back to Custom size and re-apply Fit to Page.

If you have got this correct now, and are likely to use the same size etc. again, save it as a Print Set-Up. Next time just re-call the set up and add an image to the queue.

Terry

Hi Hening,
I just went through the same exercise myself and made a nominal 600x400 mm image at 720ppi with a 1mm black border to make any cropping or white slivers more visisble.
Initially I set the page size to 600x400 but then modified it to what the queue size said with crop scissors off, down to 599.5 x 400.
I re-applied Fit to page and it was perfect after that.
I made the new image and put that into the queue and as expected QU showed 720ppi
See screen shots below:
1st is Preview and Queue data after modifying page size a little.
2nd is the same with mouse hover data.
3rd is the new image mouse hover data.
I'm sure you'll gain confidence with this; I've been a user for some time so find these tasks straight forward even though I don't use them very often.
Terry
PS, Crop scissors were OFF

> you should really go back to Custom size and re-apply Fit to Page.

I did that, and had 1 bright idea myself (this happens) - I chose Center in the button underneath the image preview. Result as before - EXCEPT that mouse over image now shows 638.9x480! AND there was no "too large" warning. So the image is OK. Still I am confused that the display at top of the preview does not show the 0.1 m reduction as exspected.

I see that you have posted in the meantime. Thank you that you go to the extent of experimenting yourself. Your results are slightly different from mine. You have the same data displayed on top of the preview as under the mouse, whereas in my example, the preview data are reduced in 1 direction, not the other - where I had exspected in either, after reading Mikes article. And after it was exactly like that in the 2 other images (verticals).

2 other differences:
How do you manage to get Crop Scissors off? Mine snap back to On when I click the BORDERLESS button. Maybe you have not done that?
Thinking over it, it occurs to me that this Borderless stuff is irrelevant since the output from Qi is not going to the printer.

And:
I have never seen the scissors icon at the bottom of the image as in your first snap.

Now I tried to avoid BORDERLESS. I discover that there are 2 places where to choose Fit to Page: Print Properties and Print Properties/Custom/Special Sizes. I clicked both.

Still, I get 479.9 mm over the preview, 480 mm under mouse and in Print Queue.

I can hardly imagine that this has anything to do with the screen resolution being too coarse - I wouldn't think that Qi gets its data from the screen??

You get 479.9mm over the preview page because the page sizes are truncated whereas print sizes are rounded as close as possible.  There is a reason for this.  When looking at a print size, you want to know within a couple decimal places how big the print is.  If a print is 479.999mm, it's OK to show it as 480mm.  BUT... you don't want to show your page size as 480mm if it is in fact a few pixels short (479.999mm) because that might prompt you to try to print a 480mm print which technically will not quite fit.  In other words, you don't want the page size to "lie" to you and tell you that there is 480mm available when it is just shy of that.  For print sizes, you don't have such a limitation and it's OK to show a rounded size even if it rounds up a little.

Mike

Thanks for clarification, Mike!