Will this ever change?

[handrawn]

Surely two completely different things here Bones - an ad is just an ad, but the car wrap that I understand Steve is talking about is art............. designed to be seen both near and far

Also to be seen in another context - galleries and museums

Sometimes this kind of art is put together from more than one print - but perhaps this is not practical if the surface is not flat - and anyway you can usually see the joins, which is not good

[Charles Moir]

Vehicle wraps are printed at anything from 300 to 1440dpi and are DESIGNED to be seen up close as well as from the street.

Ah, this is that old chestnut of people getting confused about printing resolution, especially inkjet printers.

The number of times we get customers saying, or more often just assuming, that because their printer claims to be 1400 dpi, that means they need 1400dpi printing.

THIS IS COMPLETELY WRONG

There is almost no connection between printer dpi and image dpi (or ppi)

The quoted Inkjet printer resolution has almost nothing to do with the required resolution of text and images. The actual pixel resolution (not dot) of all commercial printers, and inkjets ones is usually under 150dpi. All commercial print jobs use a half-tone screened printing process where the screen density is typically 133 to 150lpi - this means that in fact they cannot resolve more than 133 or 150 dpi for full colour artwork.

This confusion is partly as a result of printer manufactures marketing claims, partly from years of confused thinking, especially from many so called Adobe-user 'experts' that have little understanding of the science or technology, who perpetuate myths such as needing 300 dpi images for commercial printing, or worse suggesting that higher resolutions are required.

The reality is that for the highest quality commercial printing you do not need images more than 150dpi. And if you do not believe this - just try it. Do a real offset screen print job of full colour images, at 150dpi, 300 dpi and 600 dpi, and compare the results. They are all the same. Indistinguishable, even under a lens. And the reasons should be obvious. The lpi half-tone screen density of the printer (usually 150) is the finest full colour pixel density than can be resolved by that print process.

I suggest you try it on your inkjet as well. The exact same image at 150 dpi 300dpi, or higher, and see if you can tell the difference. Inkjet printers are also surprisingly low pixel resolution devices (although they tend to use stochastic dot dithering and other similar techniques, instead of a half-tone screen, to simulate fine shading). I could go into the maths of how many printer 'dots' are required to reproduce a single colour pixel, to prove the point, but a few experiments will demonstrate just as well.

You have to understand that printer dots-per-inch and photo or full colour dots per inch are NOT the same thing at all. (Adobe do at least tend to refer to screen resolution as ppi, not dpi, meaning pixels per inch, and in fact they are right to do so. We, and nearly everyone else, do not help matters by referring to image resolution as dpi not ppi).

Sorry to bust a few myths here.

So the fact is that for full colour images, even for high quality glossy magazine printing, you do not need more than 150 dpi.

So, really, honestly, for any large poster work, such as the side of vehicles, even where you expect to come right up to the artwork, you do not need more than 150 dpi, and you could easily get away with 75dpi or even a lot lower. And if the printing companies tell you different - they are wrong (and perhaps not surprisingly, because we've been developing this stuff longer than almost everyone else in the world today, we tend to find most people only regurgitate what they've been told, confuse dpi and ppi and lpi, rather than understanding the science or even doing the experiments to prove this stuff).

The above applies to color printing. For black and white text and line art printing there are different rules, but this fact remains the same: Print at 150 dpi, and at 300 dpi, or your inkjet, on vinyl (or even paper for that matter), and see if you can tell the difference when you are as close as a foot or two away. And what is the smallest text size you're going to be printing on a poster? Probably inches, hundreds of points, so really, 150 dpi, even for text printing, is way more than necessary and yes, even for close up inspection it's more than fine.

[MarcT]

Thanks for the enlightenment!


Regards,

Marc

[handrawn]

if it is bitmap or there is an element of bitmap, and the size may be varied there is sense in that

[BobInce]

I've run into this limitation a few times, and not in preparing materials for printing. When exporting large composite images, and saving larger than final size so I can supersample and scale down for better output quality.

So a fix would be useful to me, as would a built-in supersample display/export option.

[geminiguy]

Vehicle Wraps are on a completely different level than bus advertising or billboards. Steve is definitely correct

[Charles Moir]

So a fix would be useful to me, as would a built-in supersample display/export option.

There is no fix because there's nothing to fix. We DO super-sample when scaling images up (as you can see when you zoom into an image) and we bicubic sample when scaling images down. So they are the highest quality you can achieve already.

So if you want a large bitmap made from a small one (why - it's pointless surely?) then you just export at the required pixel size. And as I've just described 16,000 pixel limitation is NOT a limitation for all reasonable and practical purposes, so there is no 'fix' coming for this in the foreseeable future.

[a4hire]

Thank you Charles for busting these Myths! Good information and very enlightening.

[pauland]

Vehicle wraps are printed at anything from 300 to 1440dpi and are DESIGNED to be seen up close as well as from the street.

You need to make that small print a bit bigger Steve.. ;-)

[steve.ledger]

Ah, this is that old chestnut of people getting confused about printing resolution, especially inkjet printers.

The number of times we get customers saying, or more often just assuming, that because their printer claims to be 1400 dpi, that means they need 1400dpi printing.

THIS IS COMPLETELY WRONG

Actually, they are CORRECT, but may not know why they are. So lets look at it another way.
Bearing in mind that the next quote from Charles regarding the image dpi and print dpi IS CORRECT, consider what is ACTUALLY mean't by printers that will even print 2400 dpi, REAL 2400dpi
A pixel can have many millions of different colors and a computer screen can show all of these different colors. However a printer can not. Most (inkjet) color printers use only a small number of different inks. For example: black, red, green, blue and yellow. To create an illusion of many millions of colors, these inks have to be mixed. So to print the single pixel (that on a screen had a color depth of 16 million colors) many tiny drops of ink (or dots) are required. To accurately show the color, it may require as many as 16 drops (dots) of ink. (e.g. 4 red, 3 blue, 5 green, 2 yellow and 2 black)
So do the math here:
150dpi x 16 droplets = 2400 REAL dots per inch (dpi) on the media
Large format inkjets such as the MIMAKI JV33 are not halftone lines-per-inch (lpi) types (such as for example the Gerber Edge thermal printer which is uses at 42 - 150 lpi depending on the graphics type, and yes, you can see the 'dots' and spaces between them), they print solid colour and, have almost replaced the need to cut solid colour vinyl when constructing a sign, but look exectly the same as a sign constructed from the various vinyl colours cut in parts and assembled. A real time saver!!
These large format printers can and do easily print high quality photographs directly to whatever material you pass through the printer, whether it's vinyl, artboard, coreflute, colourbond steel etc.

There is almost no connection between printer dpi and image dpi (or ppi)

This is completey correct, I think I've been known for mentioning something like this a few times before

We, and nearly everyone else, do not help matters by referring to image resolution as dpi not ppi).

ok, so how hard then can this be to correct in Xara software??

So the fact is that for full colour images, even for high quality glossy magazine printing, you do not need more than 150 dpi.

Yes but magazine printing is not the same as large format printing for the sign industry. Stop thinking in terms of paper pages or posters here.

Sign shops are not 'publishing' print shops. There's a difference.