Design Size and Resolution

[Mike Kenny]

Hi guys,
I normally save at 25%, 300 dpi, CMYK which worked fine up to recently
i now find that if i use drop shadows in photoshop and send to printer as a Pdf it comes out as 7 channels and causes all kinds of grief!! inc washed out colours – any ideas
cheers
mike

[Jason Xuereb]

Do you get the same problem with the TIFF file format?

[Martin Oxenham]

I can’t understand why people do this saving a file at half size and double the resolution makes the actual file no smaller than full size at the right resolution.
For general signs 100dpi is good enough.

[Benno]

quote MIKE KENNY:

Hi guys,
I normally save at 25%, 300 dpi, CMYK which worked fine up to recently
i now find that if i use drop shadows in photoshop and send to printer as a Pdf it comes out as 7 channels and causes all kinds of grief!! inc washed out colours – any ideas
cheers
mike

I ‘ve heard before of this problem. It has to do something with pdf and drop shadows not working well. Same problem occurs with illustrator drop-shadows and pdf.
I normally save the document as psd or tiff and pass it to the rip.

Most of the time i use 100 dpi as well. But it really depends on the kind of application. (On very large signs i use 50 dpi, on photorealistic prints 300 dpi)

[Compilla]

150 DPI works well for me

[Jason Xuereb]

Hey Martin,

The reason I used 300dpi is because generally my photos are 300dpi. I’ve mainly done smaller signs printed and never had an issue with file sizes. But not doing larger signs fully digital I am learning to have to drop a bit.

I will do some testing soon and see what resolution I am happy with.

Cheers guys

[Bill McMurtry]

I usually do my artwork at 1/2 the output resolution for larger prints – that’s 300dpi layout for 600dpi output. At smaller output sizes (smaller than 1-2 SqM) I usually work at output resolution. Going to have to change those figures a little when the JV3 turns up next week 😀

Of course it might depend on the computer system you have. Having a fast computer with as much RAM as you can squeeze into it is a good move. Personally I don’t think 100dpi artwork is appropriate as the output can get quite blocky when scaled up – depends on the end use though.

[Jason Xuereb]

Hey Bill,

I’m upgrading my PC going to go Intel Duo Core with 2gb Ram in dual channel and a Raid 0+1 for my main drive and a dedicated SATA hard drive for my photo shop scratch disk space. Should chug along nicely then.

[Bill McMurtry]

Hey Jason, that would be a carbon copy of what I presently have. My advice would be to get 4Gb Ram 😉

[Martin Oxenham]

I’am talking about 100dpi at actual size not scaled up.
The post above says 25% at 300dpi so when scaled to full size its 75dpi to print from, but this makes no difference to the actual file size or speed of handling than if you worked at full size 75dpi

[Bill McMurtry]

Oh, OK – so you print at 100dpi?

[Shane Drew]

quote Martin Oxenham:

I can’t understand why people do this saving a file at half size and double the resolution makes the actual file no smaller than full size at the right resolution.
For general signs 100dpi is good enough.

I RIP at 25% of the size and 4x the resolution for the bigger stuff (1gb or more)

Only real advantage is that it rips faster, and when it comes to printing, the RIP engine is doing all the hard work, and not the computer.

If you have limited drive space, it does not use as much virtual memory.

I print 300dpi for signs viewed close up, 120dpi for signs viewed from a few metres away, and 75dpi for signs viewed from a fair distance away.

It depends on your market tho. I’m in the tourism market, and the client base tends to favour photo quality resolution whenever they can. I constantly hear ‘yours signs are far better quality than the stuff I’ve been supplied before’. That’s they way I like it too :lol1:

[Stephen Morriss]

Rolands book says the max you need to print at is 180 dpi for very close stuff, I’ve tried various dpi and never seen an improvment above 150 so that’s the maximum I use whatever it’s going to be used for.

Steve

[Bill McMurtry]

Stephen, do you mean artwork at max 180dpi and the actual printing at say 720dpi (rip and print at 4x artwork resolution)?

[Shane Drew]

quote Stephen Morriss:

Rolands book says the max you need to print at is 180 dpi for very close stuff, I’ve tried various dpi and never seen an improvment above 150 so that’s the maximum I use whatever it’s going to be used for.

Steve

I’m curious why they make a machine that can do much higher resolution then?

[Stephen Morriss]

quote Shane Drew:

I’m curious why they make a machine that can do much higher resolution then?

Image resolution and print resolution are 2 different things I’ve been told Shane, doesn’t mean it was right though 🙂

Yes Bill, I mean image resolution, you print at what ever you feel like.

You can download the guide from Roland DG site, it gives recommended image resolutions for viewing distances, over 10 ft they say 50ppi.
I think this is were some of the confusion comes from as their saying pixels per inch, although I would have thought it’s the same thing, a dot of colour.
As I understand it printer resolution is to do with how big the dots of ink are to get a good colour blend and gradiant, if the printer had an ink for every colour and shade it would be able to print at the same resolution as the image.

Do a search on roland_mystery_book.pdf

Steve

[Peter Normington]

Interesting read, thanks for posting that Stephen,

One of Cadlinks guys showed my a few things when visiting.

He opened an detailed image (of a watch) then duplicated it at various resolutions
between 15 and 500dpi
we then printed all the images (9) at the same size for comparison, I was quite suprised at the results (print was 720×360)

From a couple of feet away, most people would not notice the difference between the 500 and 72 dpi image, even the 50dpi image was acceptable for most usage.

I will see if I can post a picture to replicate?

Peter

[Rod Young]

quote Stephen Morriss:

quote Shane Drew:

I’m curious why they make a machine that can do much higher resolution then?

Image resolution and print resolution are 2 different things I’ve been told Shane, doesn’t mean it was right though

• An RGB display is an 8-bit device, meaning that there are 256 possible shades per colour (Red, Green, and Blue).
• Combined, these colour shades produce 256 * 256 * 256 = 16,777,216 colours.
• In other words, a single pixel of a display can produce millions of colours.
• Now, a given printer will be either a 1-bit or 2-bit machine (depending on the model).
• For a 1-bit printer, a "pixel" (i.e., a drop of ink) has two states: OFF and ON.
• This is per colour (CMYK), so a given pixel can produce 2 * 2 * 2 * 2 = 16 colours.
• For 2-bit printers, the "pixel" has four states: OFF, Small Dot, Medium Dot, and Large Dot.
• Again, this is per colour, so a given pixel can produce 4 * 4 * 4 * 4 = 256 colours.

So compare:

1. An RGB monitor display = 16,777,216 colours per pixel.
2. A 1-bit printer = 16 colours per pixel.
3. A 2-bit printer = 256 colours per pixel.

• So how does a printer produce as many colours as a monitor display? By providing a much higher print resolution (more Dots Per Inch (dpi)), so as to create the appearance of many more shades of colours per inch.
• Of course, based on viewing distance, you can elect to discard details (i.e., lower the print resolution), such that less print data is generated, thereby reducing printing time.
• In the same fashion, printer manufacturers can offer "banner printers" that specialize in fast, low-resolution reproduction.
• However, having a printer that is capable of high dpi provides the option of providing prints for your customers that are acceptable at a close viewing distance.

Cheers,

Rod at CADlink

[Gavin MacMillan]

Excellent – Some very interesting stuff, I’ve been a wee bit baffled by all this for a while, cheers people!

G

[George Kern]

as far as having issues when using .pdf files,

when you export to a PDF, there are certain options like what type of PDF to use (PDVx/1a) or whatever that shadows and stuff tend to use.