Resolution (Dpi) in print module

[George]

@Joanna

@George

In my opinion the different colors are laid at the same position . So 1 printer dot contains more droplets.

In your opinion maybe, but not in reality. If you take a strong loupe to an inkjet print, you will see that each dot has its own position. It is impossible for the inks to mix on the paper, they dry too quickly. Once again, see how pointillism works

Four inks are used: three secondary colors plus black. These ink colors are cyan, magenta, yellow and key (black); abbreviated as CMYK. Cyan can be thought of as minus-red, magenta as minus-green, and yellow as minus-blue. These inks are semi-transparent or translucent. Where two such inks overlap on the paper due to sequential printing impressions, a primary color is perceived. For example, yellow (minus-blue) overprinted by magenta (minus green) yields red. Where all three inks may overlap, almost all incident light is absorbed or subtracted, yielding near black, but in practical terms it is better and cheaper to use a separate black ink instead of combining three colored inks. The secondary or subtractive colors cyan, magenta and yellow may be considered “primary” by printers and watercolorists (whose basic inks and paints are transparent).

Color printing

Did you know that Goethe was one of the founders of modern color theory?
And that pointillism was only possible after the inventiom of the tube?
Just for fun.

George

[OXiDant (Peter)]

this is your area, mine is the technical mechanical area: (taking apart a printer and repair it if a user has a problem.
My point of view is the jpeg export resizing lower ppi does enlarge the “pixelsize” so a 1:1 conversion to “dots” does helpout enlarging the printing area.
test case A3 600DPI in printer properties.

note the image pixel resolution doesn’t change 1024x769…
Changing the printerproperties in 1200dpi doesn’t change the preview.
So it’s pure based on how many pixels i want per square inch converted in dot’s per square inch.
The lower the pixel count/inch the bigger i can print the same resolution.
(this is with the modern camera’s a non issue.)
say i have a camera which have 400x300 pixel resolution (imagine i didn’t rezise but this was max resolution…)
When use “fit to page” both has the same example size which is correct because both are same resolution.

When i ask for 72ppi it looks like this:

about 1/4 of the A4.
when i ask for 600ppi:

Conclusion of mine is ppi number is the amount of pixels you convert to 1 “pixel” (a color not the cmyk seperate but combined) on the raster in mm/inches.
The Resolution of the printer does the final conversion: how many "droplets/ toner particals it needs to create this “pixel”

The higher the PPI the more the image is compressed in preview of the printerdriver NOT in the jpeg viewer of your screen THAT uses the actual pixel x pixel resolution not the PPI.

When i working again and have the time i wil print those jpg’s in 6 ways.
1 by usb, no printerdriver only the internal; bitmapdriver, in the printer.
2 a 600dpi original size
3 a 1200dpi original size
4 a 600 dpi fit to page (A4)/A3 just what shows more)
5 a 1200dpi fit to page
using this Fast Stone image Viewer.
See which end resolution i get on A4/A3. the actual visible “horror”

(someone opend this door, i don’t call names, but i bring it to the end… )
oh to be clear i don’t print at home so i can’t use DxOPL’s “ctrl+p”
printer interface because they don’t support “print as file” (this is a actual data container which normally is directly sent to the printer as “print this” but then compiled in a filename.prn so you can store it on a USBstorage and stick it in USB directly on the printer. (this is what i do mostly so i avoid the network from the customer when i need to test something.)
other way is peer to peer connection and use my tablet. by connection in ip-range.
delay 14days i think.

[OXiDant (Peter)]

@RobEW

Thank you all for such detailed replies and conversation.

The depth of knowledge is as impressive as the diversity of opinion.

Well that’s the main problem. i am a technician reparing those buggers when they are broke and when a customer complains about quality i stick a usb in the printer and print a by my known image/pdf. This shows me if it’s the printer or the customers settings.
i ask there source file and test this the same way/ or print by my default set driver on the tablet.
if the printer is ok => my work is done. have a nice day next problem.
@Joanna and @George and @gregor are “endusers” with different knowledge of printing. (converting non sized pixels in to sized pixels/dots.)

My last post does show some “high lights” of this quest.
1 the ppi you enter in the export to jpeg is only for when you print.
it’s a parameter of which “fixed” size the image on paper will be regardless of the printers hardware-resolution. (amount of pixels you cramp in a inch which the printerdriver convert in 1inch of ink.)
This allows you to fixate the output size regardless of the printer hardware resolution and papersize. (aslong as the printers hardware resolution is more your fine. )
2 it’s only interesting to resize resolution of a image/jpg if you upload to a place where filesize is a thing. like website’s.
3 most modern printerdrivers can adjust the “ppi”, you entered in the export file (jpg properties) there selfs. just enter the Phyical size in mm x mm or cm x cm or m x m and the driver calculates the best options in the highest resolution if asked.(draft-print will lower the resolution to safe time and ink nót paper!.) (Or just use “fit to page” and select the paperszie you put in the printer.)
the PPI is handy for printing more image’s on 1 A4/A3/A2/A1/A0 and cut it later apart.

The userinterface in the "printer window (ctrl+P) " is actual developing a jpeg/tiff from your rawfile and set the ppi in the properties and sent this directly to the printerdriver which the printerdriver reads to calculate the image size on the paper. The printerdriver creates a vector or raster bitmap which is sent to the printer to follow. (and i don’t start about colorprofiles and conversionproblems you can include in this, because that’s a mind blowing rabithole.)

i hope it’s more clear now.

(when i am printed those test files you see the hardcopy results of different parameters.)

[m-photo ( Marc (macOS Sonoma on MBP16" Intel))]

@Joanna

OK. Now can you hit the “Printer properties…” button and give us a screen shot of that dialog?

Have you ever heard of Teamviewer ?
Now I wonder if there is someone on their server taking screenshots at 25 images per second to tranmit to the recipient

Congratulations for this long and detailed thread

[OXiDant (Peter)]

Teamviever?
Teamfeever…
Arghhh, internet has infected by covid19!!!
Shut down the router…

[Joanna (Joanna Carter)]

@gregor

The dpi field describes the image file. 300 is the industry standard for domestic/office inkjets printers; and its also the default value in PL3.

From experience, you can quite happily use 240 and save on ink. Apart from the dedicated pixel-peepers, most people viewing your print will not be able to tell the difference.

[George]

print size in inch = image size in pixels/resolution in ppi
You showed correctly the dpi must be read as ppi.
Changing the wanted resolution from 300 to 240 only changes the print size.

George

[Joanna (Joanna Carter)]

Indeed, but sometimes it also allows you to specify a larger print size rather than having to resample the image to get there (and it saves ink )

[George]

No, it costs ink.
Printer resolution = x.
Print resolution = y.
Every pixel takes x/y dots. The smaller y, the more dots, the more ink.

When using 240 instead of 300 the image grows 1.25 lineair. The surface 1.56. So it uses 1.56 times more ink.

George

[Joanna (Joanna Carter)]

@gregor

as it took me two years to teach myself how to print photos at a professional level (costing a lot in paper and ink on 24" Canon large format printer)

I too taught myself at the expense of wasted paper and inks. Fortunately, I only use an A3+ printer and Fotospeed’s excellent InkFlow refillable cartridges and inks

@gregor

Back to RobEW and printing from PL3: If PL3 default 300ppi is changed, the drop down list of paper sizes will not have the preprogramed document resolution size input, 300ppi, so PL3 will not be able to print the selected print size, in inches/cm/mm, correctly.

One would expect the print size would be calculated based on the image resolution and it should be possible to see the area the image takes up on the paper in the preview. The big problem appears to be that the whole printing process is based on “size to fit” with this peculiar concept of cells. Thus, you are forced to specify a cell size in mm in order to see an appropriate preview for a given paper size. Whereas, in fact, the print size should be a simple matter of a calculation based on the pixel dimensions of the image and the image resolution.

As I mentioned, it’s not even possible to specify the image resolution on a Mac, you have to calculate it and enter the printed area size as a cell size.

This is not what users, especially beginners, should have to do.

[platypus (Canon & Mac (Intel and M1))]

@Joanna

As I mentioned, it’s not even possible to specify the image resolution on a Mac, you have to calculate it and enter the printed area size as a cell size.

Let us look at it in a different way…

• Assume to print on a landscape format sheet of 100x150mm.
  Assume you want a border of 10mm each, 11mm at the lower edge.
  This will produce an image area of 80x129mm

• Set crop ratio to 80:129 (enter the values in the crop field)
  Adjust the crop position to your need

• Select paper size (borderless)
  Define margins (10/10/10/11)

• Let the printer (driver) do the rest.

This procedure has worked for me for formats that my printer can handle.
Larger prints are commissioned to a service provider.

Notes:
Recalculate numerical values according to your needs!
Due to the way that DxO presents options in the printing dialog,
I have to jump around a bit and the save settings for future use.

For above-normal-need prints, you might have to bother with ppi and dpi

[Joanna (Joanna Carter)]

As I said, this is fine when you need “print to fit”, but when you are printing on a sheet of paper that is going to fit behind an opening in a mat board to fit in a 50 x 40 cm frame, you need to respect the margins imposed by the mat board, including a small overlap, which then means you are printing to very precise dimensions and proportions that do not match the paper size. Oh, and cropping is not an option - the mat board is custom cut to fit the proportions of the image. Dealing with ppi is, unfortunately, mandatory. But it could be made easier in DPL.

[George]

@gregor

I totally understand what you are saying, as the best fine art photo/artwork printer I know of in Australia requests files be sent at 200ppi for printing on an Epson 40" large format printer.

I don’t understand that.

George

[Joanna (Joanna Carter)]

@gregor

Pixels Per Inch is the resolution of a digital file. Dots Per inch is the resolution of the reproduction of a digital file; as a photo, on a screen or projected onto a projection screen.
The printer mentioned has his equipment set up where he can print fine art quality prints from 200ppi.

And, if I may add, it’s all about resolution vs viewing distance. The printer in question obviously is printing larger prints, which are meant to be viewed from further away and, thus, do not need the same pixel density to appear smooth to the viewer. Here’s an article that gives you some idea of how that works

[George]

I’ve a technical background so I’m very keen on units.
A digital image only has a size in pixels, non metric.
It gains a metric size when printing or on screen by example.
What is called image resolution is a demand to the printer to print a file on, let’s say, 200ppi. It’s not a property of the image.
When you ask the printing company to print to a fixed size, the printing company could say you minimal so many pixels to gain the quality we would like to deliver.
Could you give a link to that company?

George

[Joanna (Joanna Carter)]

@George

What is called image resolution is a demand to the printer to print a file on, let’s say, 200ppi. It’s not a property of the image.

It’s not strictly a demand directly to the printer, it has to pass through the printing software and the printer driver. The printing software then calculates the physical print size from the size in pixels divided by the ppi and sends the resulting data to the printer.

[George]

I don’t see the difference. It’s ok for me.

George

[OXiDant (Peter)]

i was looking at a explanation about “cell size” and stumbled on this:

Print images and manage colors with DxO OpticsPro 9 - DxO

The text:

3.3 – Adjust the size of the cells and the captions

To adjust the size of the cells and the spacing between them on a PC, use the Height and Width sliders in the Cell size palette; on a Mac, enter a value in the input fields in DxO – Layout > Cell Size > Specify cell size .

To caption each cell, choose Image name and date rather than displaying the shot metadata (which tends to be only of interest to you, and which you can find in the DxO Optics Pro EXIF palette).
Still NO CLUE what it says.

So top to bottom:
“Printersettings”:
logic apart from dpi, two things enter doesn’t show the 200 dpi when changed i must click on an other feature/setting to get it. Two: It should handle the pixels per inch (amount of undimentioned pixels in a inch so the printer can scram that info in a dimentioned, by its own native resolution, dotted /inch. preview doesn’t show.
( a 400x300 jpeg would be changing in preview when i change amount of pixels/inch. (change the size of the existing pixels to fit in a A4/A3.) It keeps full spread.
“color and Sharpnes” for anyone who is playing with colorprofiles. Sharpnes? USM? (confirmed by the text.) this is something i would let handle by the printer unless i am confident to handle it better.
Layout: contact printing and multi image on one sheet.
Margins well any one knows that, the non printed area’s between paper edge and image’s inbetween.

Cells? of the row raster from layout? What?
help guide:
" Cell size

The Height and Width sliders let you make the following changes so you can adapt the page or pages to the content that you want to print:

• Single image : One lone image on the page is a cell by itself; use the height and width slider to move the image horizontally and/or vertically.
• Multiple images or contact sheets : Use the sliders to modify the size of the image cells as well as the spacing between the cells, both horizontally and vertically."
  Eh can’t i do the same with raster layout and margins? And i am need to use “cells” to skrink the image on the page wile i expect this behaviour with “resolution adjustment”.
  If you see this video
  Margins: ONLY margins of the Sheet not in between the “cells” the printer can handle this so is this connected? or overrulls the printerdriver the software?
  And Cells? again printer can do this also:
  

What is miss in this window is:
Actual reaction in the “preview of my print” when i change resolution in dpi. (i change my print"resolution" so i want to see this in my preview.

A “100% view” in preview, if i can change a thing as print resolution for foto’s i thunk i like to forcast how this will look on paper when printed. (Say when i use my trusted “loup” that enlargement factor. in fact create a software loup.) Printing a A0 and discover you need a bit more DPI well i would be mift trowing that piece away and print again.

A preview is a preview of the “print” not a sheet with layout examples.
if this is the case the User interface needs to interact with the printerproperties. (which settings is done in my printer to enhance/lower the result) or atleast let you choose which will be leading the show. (sharpening is one of them by laserprinters)

it’s a mixed bag for me this print interface.
as techy i mis the real preview when i use the “resolution-slider” so it’s a trial and error based concept.
I expect to see differences in size in this case:

See the ppi’s differes and resampling is also a factor, but non of this is visible in the preview…
As almost never print myself (at home) i like the easy layout.

[RobEW]

Brilliant. So there were some proper instructions from DXO in the manual for a predecessor of PhotoLab, but they seem not to be in the manuals for the current product. Are DXO here to comment?

[OXiDant (Peter)]

@gregor

Exactly

And eye sight aka glasses.