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Author Topic: Images not centered properly  (Read 14674 times)
ripek
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« on: January 29, 2013, 04:03:25 PM »

I'm trying to print a series of album spreads. The image is 60x30cm on 61cm (24") paper.

Here is my setup:

http://marcinbittner.com/luzem/center_setup.jpg

The image is 600x300mm + 1mm red border + 5mm green border. QI says the total is 601.2 x 301.2 mm = all is correct.
The paper is 610mm in width in real life and same goes for the print properties. The size of the space is 610x310mm.

The placement of every spread is CENTER. Not optimal etc.

PROBLEM?



There is a difference in the center placement. Sometimes its up to 3mm. I thought that it might be a paper issue but I try to fit is as much as possible to the holder. Repeat tapping etc.
I see no visual problems there.

Any clues?
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Fred A
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« Reply #1 on: January 29, 2013, 06:46:30 PM »

Quote
The image is 600x300mm + 1mm red border + 5mm green border. QI says the total is 601.2 x 301.2 mm = all is correct.
The paper is 610mm in width in real life and same goes for the print properties. The size of the space is 610x310mm.

I admit not being very comfortable with mms, but I am having a problem again trying to simulate.

600mms + a 1mm border = 602mm  + a 5mm border= 612 mms

300mm = 1 mm border = 302mms plus a 5mm border= 312mm

The picture looks like paper shift inside the printer if I am looking at a snap of a ruler lying on prints.??

Fred
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ripek
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« Reply #2 on: January 29, 2013, 07:21:09 PM »

Ups my bad.

The image is 600 x 300mm. Red border is 0.1 mm and green is 0.5mm - it's visible in the picture.

600 + 0.1 + 0.1 + 0.5 + 0.5 = 601,2mm  - I just measured it and in fact its 601.5 (more or less).

I just want to be sure that QI places the image exactly in the vertical / horizontal center of the given space - which is 610 x 310mm

I just checked the roll :


If you can assure me it's not the software I'll look up the hardware. Once I put the roll in I can slightly push it left or right. Maybe that is the issue here?
I just placed a cardboard strip - maybe it helps:


Anyone had a similar troubles? Ipf6350

I need that sorted out because we just set up our folder to 305mm (half) and we get all kind of variations Sad(

« Last Edit: January 29, 2013, 07:24:52 PM by ripek » Logged
Fred A
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« Reply #3 on: January 29, 2013, 08:21:49 PM »

Quote
I need that sorted out because we just set up our folder to 305mm (half) and we get all kind of variations
OK Glad we got that size business and borders sorted. Now I can simulate what you are doing.

I see one boo boo
First of all, please place your image ready to print in the queue.
Next go to the PAGE EDITOR. Click on the LOCATION TAB.

You can see from my screen snaps

The print size is the same as yours; 601.2 x 301.2
The location is showing 4.4 mms all the way around (Centered)   BUT! If I use Center placement it will shift. So use what I show Optimal Spaced. Then it sets even all the way around.

The page size matches yours, and you can see the print size in the screen snap of the queue.

Maybe it will help.

Fred
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ripek
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« Reply #4 on: January 29, 2013, 08:35:56 PM »

I have already another album in the printer. This one is 10" = 508 x 254mm on the same 610mm roll.

When I go to size/loc I get this:



I just have to click {CENTER} and then pick Placement: [OPTIMAL] ?

And do I have to do it every time I start printing? Seems like a lot of extra work. I mean shouldn't QI just figure out that "CENTER" means center in relation to everything?

It doesn't have to be dead in the center in the end. I'm more concerned about variations in the aligment. Don't know yet if that is the issue with QI or that moving roll holder...
« Last Edit: January 29, 2013, 08:38:17 PM by ripek » Logged
Fred A
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« Reply #5 on: January 29, 2013, 08:58:05 PM »

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I just have to click {CENTER} and then pick Placement: [OPTIMAL]

You don't click the Center button, just set placement to

OPTIMAL SPACED is the one you want. No extra work. QU remembers it until you change it.
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ripek
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« Reply #6 on: January 30, 2013, 07:00:23 AM »

I'll print some today and let you know. Thanks!
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ripek
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« Reply #7 on: January 30, 2013, 07:07:51 AM »

One more Q. How is going to placement tab and selecting OPTIMAL from just selecting OPTIMAL option from the dropdown menu in the main program window?

I did use that option but it gave variation up to 4mm!

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Fred A
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« Reply #8 on: January 30, 2013, 10:16:37 AM »

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I did use that option but it gave variation up to 4mm!

OK. This is what's next!
You selected OPTIMAL SPACED...   There is an OPTIMAL selection, but we want Optimal Spaced... !!
I have roll paper selected/
I have a page size selected of 610 mm x 310 mm
I have a print size selected of 601.2 x 301,2 (Same as yours print. You have some borders mixed in, but the total print size is the same.)
I just didn't bother with borders but have the same print size.

Now look at my screen snap of the Page Editor and the location showing 4.4 mm of space all the way around.
I just made a simulated print to the Print preview of the driver.... Equal sides!
I deleted the print from the spooler, and replaced the image in Qimage with a different one...
Rechecked,    4.4 mm all the way around.

Have a good look at the Page Editor Location Tab, before you click Print.  If it matches my 4.4 mm margins, then you are fine, ready to print.
If it comes out different on the paper, I would look for "slop" in the feed mechanism, guides or something in the printer.

Best I can do from here.
Fred
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ripek
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« Reply #9 on: January 31, 2013, 06:13:42 PM »

I did a little test.

I have a simple 600x300cm image with a line right in the middle of it. You can download it here: http://www.marcinbittner.com/luzem/600x300mm.jpg

The point is to print that vertical line on the 305'th milimeter of the paper.
I have a 700mm ruler to measure everything.

Every spread below was measured. Every spread is 610mm long (24")

CASE ONE:
- Optimal Spaced
- 0.2 red border B   (not B+)
- 6 spreads added to the queue and printed
The SIZE/LOC shown equal 5 / 5 / 5 /5

Results of the placement of vertical line:
304,5
304,5
304,0
303,5

CASE TWO
- Center
- Red border or no border - same results
- The size/loc shows 4.9 4.9 5.1 5.1

10+ spreads with perfect 305mm line..


I'm puzzled. You told me Optimal spaced yet the center placement is correct.

Does that have to do with a fact that I put 610mm paper into paper size and in fact paper is sometimes 609.6? If it was problem with a printer I couldn't hit 305 line every time on CENTER placement.
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rayw
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« Reply #10 on: February 01, 2013, 02:33:47 PM »

Hi,

At first sight it looks like either the paper feed on printer is skewed, or qimage does something odd with queues and spacing (fp rounding errors?) in conjunction with printer driver. The first thing to do is to verify that the printer feeds are correct. The driver will most likely have settings for that. Then, print your image line with something basic, e.g. irfan view, a number of times, and check that it is consistently spaced from one edge - that should highlight the effect of paper feed wobble. (Instead,  I suppose you could instead print the inbuilt nozzle check images a number of times, and see if they are spaced the same from the edge of the paper). Then, without putting it in the queue in qi, print again, a number of times, see if wobble is the same. Then do it in the qi queue. if the error is only when in the qi queue, then that will be up to Mike to fix (try instead of mm, use inches, (whole numbers, not decimals) and don't worry about the centre, just need to check distance from edge is consistent- it may be an inch/mm thing.)

I think you have to try and isolate where the problem lies, hardware, software or paperware. I think, for most printers/papers, a half mm variation could be expected, but it looks as if your errors are accumulating. If it is hardware/paper, then you should be able to see where the edge of the paper is at start and end of the print run. (If the line is long enough, you may be able to measure the distance variation between top and bottom of line to edge).

Personally, I would not be bothered by a mm or two variation with roll canvas, but if at the end of of a run the error came to 5mm or so, then that could be a nuisance.

Best Wishes,

Ray
« Last Edit: February 01, 2013, 03:34:16 PM by rayw » Logged
ripek
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« Reply #11 on: February 01, 2013, 04:10:25 PM »

Yes, with canvas no problem but try to print a wedding album spread that has framed images close to middle fold line. Even 0,5mm error is visible like hell ... Sad(
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Fred A
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« Reply #12 on: February 01, 2013, 06:46:58 PM »

Quote
(try instead of mm, use inches

Hmm Ray, good idea

23.67 x 11.86 inches

I would try setting to inches after you are all set to print.
I did it here in the driver only as I don't have the printer, and now I don't get any change in margins anymore.

Worth a try.
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rayw
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« Reply #13 on: February 01, 2013, 08:58:02 PM »

If you think about , it's amazing that this stuff works at all. Industrial printers, the ones that use printing inks on rolls of paper, offset litho, etc. are pretty/solid  heavy machines in order to maintain exact alignment of the colours, and they are working generally on single cut sheets. Newspaper printers - offset web for example, are massive. Even then, they do not need the accuracy of placement that we are talking about with our low cost equipment, since usually the paper is guillotined to size after printing. Our inkjets are built of pressed steel and plastic, but we still expect extreme accuracy in all conditions. Changes in temperature and humidity effects paper and other materials, which we often don't consider.

A back of an envelope very, very rough calculation gives some interesting figures. Printing a 6 metre length, with an error in feed roller alignment to result in less than 1mm variation from beginning to end of the 6 metres, means the roller axis must be perpendicular to the paper feed to within 0.01 of a degree. If the roller axis is adjustable, if it were a metre long, then it would need to be adjustable to within about 0.0001mm. (If it was adjusted by a simple screw of, say 1mm pitch, then could you turn it 0.0001 of a revolution?).

So, we rely on perfect, even width sheets or rolls of paper, being precisely fed through accurate guides set correctly (whatever that means - too tight, paper buckles/jams, too slack, paper skews).

Not saying that this is the cause of the problem here, but just saying that I think we sometimes may expect too much of of our gear, which generally has been built down to a price.

Best wishes,

Ray
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