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Hello, I have a simple question that may have been addressed before. I use Epson Print Layout for printing on quality paper. I need high resolution printing, ie high Dot Per Inch. With this application it is easy to fix a precise print size but the DPI must be embedded in the file to be printed. Now how can I set (resize) the file so that I can print at high resolution without making the file monstrously big? A small print like 11 x15 at 1440 DPI can get huge, in the GB range.

Scaling do not seem to work since increasing the DPI reduces the size of the print.

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Hi srg,

Which Affinity app are you using?

Unless i'm mistaken, you should be able to do this in Affinity Photo.  Open the image and then click Document>Resize Document, uncheck the resample box and enter 1440DPI then if you export this out as a JPG with the metadata embedded the DPI value will be 1440 DPI :)  but the image dimensions will not have changed.

Hi, stokerg

Not sure what is going on but I got your  email but I do not see the post.

In any case I use AP and no, that does not work. The DPI change with changing the size of the image. This is the problem I am having.

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Hi srg,

I need to apologize to you, my reply was wrong and i've hidden it.  As i've explained on PM, my answer was wrong and i'll need to seek help tomorrow on this, as i'm not sure what to do in this case :44_frowning2:  But i'll get you an answer and will update here tomorrow :) 

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On 8/29/2019 at 4:20 PM, srg said:

Unless i'm mistaken, you should be able to do this in Affinity Photo.  Open the image and then click Document>Resize Document, uncheck the resample box and enter 1440DPI then if you export this out as a JPG with the metadata embedded the DPI value will be 1440 DPI :)  but the image dimensions will not have changed.

 

Hello srg,
Short answer, yes that’s correct, if you just want to change DPI metadata in the image.

It may help to not look too closely at the top two size fields in the Resize panel when changing just DPI metadata.
Instead just look at the info being displayed at the bottom of the Resize panel. The numbers in brackets to the right are the actual pixel dimensions of the file.
For comfort you may want to check the pixel dimensions before changing DPI data and again after entering the new DPI before committing to the new DPI by clicking the ’Resize’ button.

Before.png.2ccb6a0f679a0fbec2e9f7f300e25a0b.pngAfter.png.74c41515b013539ec72c79283c278038.png

You may be interested in this article about DPI too: http://shootmyart.com/dpi-myths/


macOS 10.14.6  15" Macbook Pro, 2017  |  4 Core i7 3.1GHz CPU  |  Radeon Pro 555 2GB GPU + Integrated Intel HD Graphics 630 1.536GB  |  16GB RAM  |  Wacom Intuos4 M

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Thank you, that is exactly my point and my question is not answered.  If I want to change only the DPI as the AP help suggests the size changes too, i believe because DPI are in effect PPI in the resize window. 

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In my previous post you can see that the size of the image I was using did not change. It started 3369px X 2144px and it finished 3369px X 2144px.
The physical size that it might be printed at later though is entirely up to me.
The DPI data in an image is used as a guide to tell printers what they should be aiming for.
Assuming that 1 pixel = 1 ink dot, then the “Size” being shown in AP is only letting me know that, given the number of pixels in my image and if I really do want the printer to put down 1,440 ink dots every inch when reproducing it, then my image of 3369px X 2144px is going to print quit small.
But physical image sizes like inches, centimeters, etc… are purely hypothetical, they don’t exist while an image is in a computer. The image only has pixels.
When printing the only question I have to ask myself is “Do I have enough pixels in my image for the printed size I want to look good?”
3369px X 2144px printed at A4 using 72dpi or 1440dpi, would look good.
Printed at A1 and even the 1440dpi version is not going to look good close up because I didn’t have enough pixels to start with for a print at that size when viewed close to.

Have a look at the table at the bottom of this page for a reasonable overview of number of pixels v print quality: http://www.urban75.org/photos/print.html


macOS 10.14.6  15" Macbook Pro, 2017  |  4 Core i7 3.1GHz CPU  |  Radeon Pro 555 2GB GPU + Integrated Intel HD Graphics 630 1.536GB  |  16GB RAM  |  Wacom Intuos4 M

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On 9/10/2019 at 4:26 PM, markw said:

Hello srg,
Short answer, yes that’s correct, if you just want to change DPI metadata in the image.

It may help to not look too closely at the top two size fields in the Resize panel when changing just DPI metadata.
Instead just look at the info being displayed at the bottom of the Resize panel. The numbers in brackets to the right are the actual pixel dimensions of the file.
For comfort you may want to check the pixel dimensions before changing DPI data and again after entering the new DPI before committing to the new DPI by clicking the ’Resize’ button.

Before.png.2ccb6a0f679a0fbec2e9f7f300e25a0b.pngAfter.png.74c41515b013539ec72c79283c278038.png

You may be interested in this article about DPI too: http://shootmyart.com/dpi-myths/

Thank you. I believe i have rather clear the difference between Dots Per Inch and Pixels Per Inch. The problem is  that AP uses DPI  instead of PPI, in fact these two entities should be non-homogeneous and therefore non-divisible instead they are: in your example 3369 Pixels divided by 1440 equal 2.34.

In conclusion if i want to embed a high value of DPI (for the printer) i MUST resample the image getting humongous file dimensions. This is not what I thought the AP help was saying.

all the best to all.

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16 hours ago, srg said:

The problem is  that AP uses DPI  instead of DPI ...

You might want to edit that.


Affinity Photo 1.7.2, Affinity Designer 1.7.2, Affinity Publisher 1.7.2; macOS High Sierra 10.13.6 iMac (27-inch, Late 2012); 2.9GHz i5 CPU; NVIDIA GeForce GTX 660M; 8GB RAM
Affinity Photo 1.7.2.153 & Affinity Designer 1.7.2.6 for iPad; 6th Generation iPad 32 GB; Apple Pencil; iOS 12.3.1

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On 8/28/2019 at 8:33 PM, srg said:

Scaling do not seem to work since increasing the DPI reduces the size of the print.

From the help file:

"Scaling will embed a specific print resolution into an image's metadata to force it to print at a specific dpi (e.g. 300 dpi). The image's pixel dimensions remain unaffected"

 

... BUT NOT the dimensions. Which is logical.


 


Affinity Photo  1.7.2.471 

Windows 10 Home  1903 (build 18362.175) - 64 bit processor - AMD A4-5000 APU with Radeon HD Graphics  1.50GHz - RAM 8,00 GB
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40 minutes ago, HVDB Photography said:

From the help file:

"Scaling will embed a specific print resolution into an image's metadata to force it to print at a specific dpi (e.g. 300 dpi).

As @markw already mentioned, the "force it to print at a specific dpi" part is not really accurate since it is quite possible to ignore the DPI metadata during printing.


Affinity Photo 1.7.2, Affinity Designer 1.7.2, Affinity Publisher 1.7.2; macOS High Sierra 10.13.6 iMac (27-inch, Late 2012); 2.9GHz i5 CPU; NVIDIA GeForce GTX 660M; 8GB RAM
Affinity Photo 1.7.2.153 & Affinity Designer 1.7.2.6 for iPad; 6th Generation iPad 32 GB; Apple Pencil; iOS 12.3.1

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7 hours ago, HVDB Photography said:

From the help file:

"Scaling will embed a specific print resolution into an image's metadata to force it to print at a specific dpi (e.g. 300 dpi). The image's pixel dimensions remain unaffected"

 

... BUT NOT the dimensions. Which is logical.


 

Yes it is logical but only if the DPI are the same thing as the PPI

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3 minutes ago, srg said:

Yes it is logical but only if the DPI are the same thing as the PPI

DPI & PPI are not the same thing. In fact, DPI doesn't even mean the same thing in different contexts because a "dot" doesn't mean the same thing in different printing contexts. The same is true for PPI because it is a physical measurement applicable only to physical objects like computer displays & even for them a 'pixel' can refer to a triad of bars or some other arrangement of a different number of color producing elements.

The only thing that is context-independent is pixel dimensions, but even for that pixels are not always square so there can be a certain amount of ambiguity in the conversion of pixel counts to linear dimensions even in the virtual realm.


Affinity Photo 1.7.2, Affinity Designer 1.7.2, Affinity Publisher 1.7.2; macOS High Sierra 10.13.6 iMac (27-inch, Late 2012); 2.9GHz i5 CPU; NVIDIA GeForce GTX 660M; 8GB RAM
Affinity Photo 1.7.2.153 & Affinity Designer 1.7.2.6 for iPad; 6th Generation iPad 32 GB; Apple Pencil; iOS 12.3.1

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1 hour ago, R C-R said:

DPI & PPI are not the same thing. In fact, DPI doesn't even mean the same thing in different contexts because a "dot" doesn't mean the same thing in different printing contexts. The same is true for PPI because it is a physical measurement applicable only to physical objects like computer displays & even for them a 'pixel' can refer to a triad of bars or some other arrangement of a different number of color producing elements.

The only thing that is context-independent is pixel dimensions, but even for that pixels are not always square so there can be a certain amount of ambiguity in the conversion of pixel counts to linear dimensions even in the virtual realm.

Yes in fact i should have said: Yes it is logical but only if the DPI are assumed to be the same thing as PPI

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