How to change canvas size to standard size

[caliandris]

I'm probably being dense.  I'm trying to set a canvas size to A5.  I can see that I can set a size in centimetres, but the problem I'm encountering is that if I want to reduce the number of pixels from the thousands, it changes the size of the canvas and is no longer A5.  The two things seem to be linked together and I can't work out how to be able to set the canvas size and make it stick....

[HyReZ]

An ISO A5 document has a form factor of 148 x 210 mm or 5.8 x 8.3 in
Set your Canvas to 5.8 x 8.3 inches and use the default resolution setting
Your document will print at the correct form factor if you do not change it
when you use a quality printing utility. 

You can test this empirically by creating an image in the ISO-A5 format

and print it using the PrintIt.Effect v0.9 plugin. (The Windows 10 Print Pictures utility

is not professional quality and it is not accurate!)
Get a ruler and measure the image on the page after using the Print It plugin.
https://forums.getpaint.net/topic/28520-print-it-tools-effect/
 

Make sure that in the Print It layout option; the setting of the Image Size is set to [Use 'Print Size' of image]
Whether you choice 300 DPI or 600 DPI here will not change the image dimensions (At least not on a color

laser printer, which is what I use). DPI (Dots Per Inch) is print resolution and not print dimension! (Just as placing

grain of salt under a microscope, does not alter the dimensions of the salt grain). Also remember that monitors

and image sensors use pixels and printers use dots or drops of ink (DPI), they are not the same!

Edited April 10, 2019 by HyReZ
Correcting spelling and adding more nfo!

[Ego Eram Reputo]

In short:

 

Print Size (inches) = Image Size (pixels) / Print Density (DPI aka Dots per Inch)

 

Equally, but using a different unit of measurement.....

 

Print Size (centimeters) = Image Size (pixels) / Print Density (DPcm aka Dots per Centimeter)

 

Another way of writing the second equation is....

 

Image Size (pixels) = Print Size (centimeters) *  Print Density (DPcm aka Dots per Centimeter)

 

In either case, if you want A5 size with fewer pixels, lower the DPI setting 😉

[HyReZ]

Even shorter:
If you divide an inch into 96 parts or if you divided it into 600 parts, it is still an inch!

[Ego Eram Reputo]

@HyReZI'm trying to make this clearer. That kind of comment is not helping 😐 

[HyReZ]

Okay then, let's make it clear together!

ISO-A5 is a dimension and not a resolution. That dimension can be filled with a low or high resolution image, or even a single color. If resolution is the priority then reducing pixel count is a bad idea. Best advice is to set the dimension of ISO-A5 (5.8 x 8.3 inches), lock in this aspect ratio, and create a canvas large enough to produce an image that has the resolution needed to produce a good print in that form factor. If it means having a file size of 3480 x 4980 pixels, that is okay because it will still print to ISO-A5 with a good printing app!

Edited April 11, 2019 by HyReZ

[Ego Eram Reputo]

Caliandris specified A5 size AND a fewer pixels. Lowering the print density (DPI) is the only option.

 

It is likely that after printing the results will be less than impressive because of the low resolution. But this is not what has been asked.

[HyReZ]

@Ego Eram Reputo

I will agree with that!

I will offer Caliandris this to consider and will be done here:
I have a camera that produces a 20 megapixel image.
I can have my printing software produce a wallet size print or a tabloid size print from the same image data.
I do not have to reduce the number of pixels in my image file to produce that result, 

I just have to print to the desired form factor!

[caliandris]

Thank you for all your answers.  OK, I understand not to mess with the resolution if I want my dimensions in centimetres to stick, and I understand that the print resolution is something separate from the number of pixels.  I had assumed that dots per inch would somehow translate to pixels per centimetre in some logical way which would allow me to convert one to the other, I hadn't realised that they were entirely divorced from each other.  I'll leave well alone and stick to setting my dimensions in centimetres!

[caliandris]

OK, I'm back again.  I set the dimensions in the box on making a new document.  I set them at 16.4 centimetres and 22.6 centimetres to allow for 3mm bleed all round and 5mm all round to include crop marks outside the image area.

 

When I chose to view it actual size, the image wouldn't fit on the screen!  I checked that I hadn't inadvertently altered the dimensions by pasting in something larger, and the dimensions were still set as I had entered them.  But the image is HUGE.  I knew it was not just the display which was going crazy because when I came to type in text for the document I was trying to lay out, it needed 95pt text to be readable - and even then it wasn't that big.  I don't understand what's going on.  When I print that image, even though I have unchecked the box to make it fit to the page, I get an almost A4 image with a very small border - and it is a lot smaller than the "actual size" image on the screen.  I'm perfectly happy to believe I'm doing something stupid to cause this to happen, but I'd be grateful if someone can work out what on earth it is I have done....

[HyReZ]

Are you using the Windows print utility or the Paint.NET Print It plugin in?

[Ego Eram Reputo]

6 hours ago, caliandris said:

When I chose to view it actual size, the image wouldn't fit on the screen!  I checked that I hadn't inadvertently altered the dimensions by pasting in something larger, and the dimensions were still set as I had entered them.  But the image is HUGE. 

 

People are often surprised how much image must be provided to print at a decent quality. Remember, monitors usually show images at 1/3 the density of printing. Don't be afraid! Sounds like your image is correct.

 

Best bet? Do a quick border and print it to check alignment and size. If printing from within PDN use the PrintIt plugin.