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Change DPI without resizing the image not possible

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I want to change an image with 300 DPI to 72 DPI. This is not possible. If I open the converted image again it show 300 DPI.
I think this is essential but for this simple operation I have to use Irfan View.

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7 hours ago, Opera said:

I want to change an image with 300 DPI to 72 DPI. This is not possible. If I open the converted image again it show 300 DPI.
I think this is essential but for this simple operation I have to use Irfan View.

When Exporting the image, you will need to click the More... button and then uncheck the "Embed metadata" box. There is a bug logged with the Serif team about that, but it is not fixed yet.


-- Walt

Windows 10 Home, version 2004 (19041.388),
   Desktop: 16GB memory, Intel Core i7-6700K @ 4.00GHz, GeForce GTX 970
   Laptop:  8GB memory, Intel Core i7-3625QM @ 2.30GHz, Intel HD Graphics 4000 or NVIDIA GeForce GT 630M
Affinity Photo 1.9.1.979 and 1.9.1.979 Beta   / Affinity Designer 1.9.1.979 and 1.9.1.971 Beta  / Affinity Publisher 1.9.1.979 and 1.9.1.967 Beta

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8 hours ago, walt.farrell said:

When Exporting the image, you will need to click the More... button and then uncheck the "Embed metadata" box. There is a bug logged with the Serif team about that, but it is not fixed yet.

Thank you Walt,
unfortunately this bug exists ever since I bought AP. This problem was communicated many times. So for me AP is just an ambitious toy - playing around with from time to time only for the simple reason that some basic key features are sorely missed.
DPI converting is not even implemented in the patch function. This function is essential for patch converting also.
Don't get me wrong. Affinity is an ambitious project and I hope the essentials of image editing (a fully working Standard Image Resizing dialog, correct embed metadata) will also be implemented soon.
In the meantime I have to use Irfan View to resize my images. Hmmm....

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On 8/24/2018 at 1:42 AM, walt.farrell said:

When Exporting the image, you will need to click the More... button and then uncheck the "Embed metadata" box. There is a bug logged with the Serif team about that, but it is not fixed yet.

It is not about exporting, but at the time of working on the image.


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2 hours ago, Petar Petrenko said:

It is not about exporting, but at the time of working on the image.

I'm sorry, Petar, but I don't understand that comment. Can you explain a bit more, please?


-- Walt

Windows 10 Home, version 2004 (19041.388),
   Desktop: 16GB memory, Intel Core i7-6700K @ 4.00GHz, GeForce GTX 970
   Laptop:  8GB memory, Intel Core i7-3625QM @ 2.30GHz, Intel HD Graphics 4000 or NVIDIA GeForce GT 630M
Affinity Photo 1.9.1.979 and 1.9.1.979 Beta   / Affinity Designer 1.9.1.979 and 1.9.1.971 Beta  / Affinity Publisher 1.9.1.979 and 1.9.1.967 Beta

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4 hours ago, walt.farrell said:

I'm sorry, Petar, but I don't understand that comment. Can you explain a bit more, please?

Not in "File > Export" but in "Document > Resize Document".


Dell Inspiron 7559 i7    Windows 10 x64 Pro
Intel Core i7-6700HQ (3.50 GHz, 6M )    16GB Dual Channel DDR3L 1600MHz (8GBx2)    NVIDIA GeForce GTX 960M 4GB GDDR5
1TB HDD + 128 GB SSD Hard drive    UHD (3840 x 2160) Truelife LED - Backlit Touch Display

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22 minutes ago, Petar Petrenko said:

Not in "File > Export" but in "Document > Resize Document".

Thanks. I believe that Opera was asking about the Export problem.

I'm not aware of any issue with changing the DPI via Document > Resize Document.


-- Walt

Windows 10 Home, version 2004 (19041.388),
   Desktop: 16GB memory, Intel Core i7-6700K @ 4.00GHz, GeForce GTX 970
   Laptop:  8GB memory, Intel Core i7-3625QM @ 2.30GHz, Intel HD Graphics 4000 or NVIDIA GeForce GT 630M
Affinity Photo 1.9.1.979 and 1.9.1.979 Beta   / Affinity Designer 1.9.1.979 and 1.9.1.971 Beta  / Affinity Publisher 1.9.1.979 and 1.9.1.967 Beta

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22 minutes ago, walt.farrell said:

Thanks. I believe that Opera was asking about the Export problem.

I'm not aware of any issue with changing the DPI via Document > Resize Document.

All of us are used to PS. And Photo's "Document Resize" (which should be renamed to "Image Resize") doesn't work the same way as in PS.


Dell Inspiron 7559 i7    Windows 10 x64 Pro
Intel Core i7-6700HQ (3.50 GHz, 6M )    16GB Dual Channel DDR3L 1600MHz (8GBx2)    NVIDIA GeForce GTX 960M 4GB GDDR5
1TB HDD + 128 GB SSD Hard drive    UHD (3840 x 2160) Truelife LED - Backlit Touch Display

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I'm not used to PS, and as far as I'm concerned  Affinity Photo's Document Resize works just fine :)

However, I'd like to see Serif fix the metadata bug.


-- Walt

Windows 10 Home, version 2004 (19041.388),
   Desktop: 16GB memory, Intel Core i7-6700K @ 4.00GHz, GeForce GTX 970
   Laptop:  8GB memory, Intel Core i7-3625QM @ 2.30GHz, Intel HD Graphics 4000 or NVIDIA GeForce GT 630M
Affinity Photo 1.9.1.979 and 1.9.1.979 Beta   / Affinity Designer 1.9.1.979 and 1.9.1.971 Beta  / Affinity Publisher 1.9.1.979 and 1.9.1.967 Beta

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Resizing is a bit of an ambiguous expression.

An image has a size in pixels, but pixels have no dimension in inch or cm. Changing the number of pixels however, is certainly seen as resizing.

If you want to print an image, then the actual size of the print will be determined by the size of the image in pixels, and the dpi setting.

If you have an image of 600 x 600 pixels, and a setting of 300 dpi, then the resulting image on paper will be 2 x 2 inch. Change the dpi setting to 150 dpi, and the print will be 4 x 4 inch.

So changing the dpi setting of an image is also seen as resizing. Even though the pixels are not even touched, the size of the resulting image on paper will be changed.

To sum it up, resizing can mean changing the number of pixels, changing the dpi setting, or both at the same time.

The dpi setting is stored in the TIFF headers, or in the EXIF headers, but not in both. It is no more then comment really, it doesn't do anything with the pixels.

The topic starter is rightfully complaining that changing the dpi setting (= rewriting the dpi setting in the headers) doesn't work in AP. That is indeed a very silly and annoying bug that should have been resolved long ago.

 

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Hi @grunnvms,

I agree with you 100%. I want just to clarify this matter a little bit further.

If you ask any camera manufacturer at what value they set the DPI of the pictures taken by their camera, they will say: "we set no value". And it is true because the real resolution of the picture is its size in pixels. So, if the camera takes 12 MP pictures, the resolution is 4000 x 3000 px and the DPI must be 0 when you open the picture in any bitmap app. There are two cases:

  1. if you want to use the picture for web, then you have to lower its real resolution to some value appropriate for web (the DPI is still 0), lets say 400 x 300 px for faster scrolling. This case is destructive, because you will not be able to return its real resolution if you save the picture on the disk (unless you've made a copy of it);
  2. if you want to print the picture then you must not change its resolution (it stays 4000 x 3000 px all the time). You change the DPI value to determine how many pixels you want to pack into one inch (or some other real world unit). In this case the app should show you the real world values to see how long and wide would be your picture when printed.

In both cases the picture resolution should be seen all the time to inform you if you are doing the changes the right way or not.


Dell Inspiron 7559 i7    Windows 10 x64 Pro
Intel Core i7-6700HQ (3.50 GHz, 6M )    16GB Dual Channel DDR3L 1600MHz (8GBx2)    NVIDIA GeForce GTX 960M 4GB GDDR5
1TB HDD + 128 GB SSD Hard drive    UHD (3840 x 2160) Truelife LED - Backlit Touch Display

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Thanks Petar,

I get you points, but I do have some remarks.

Cameras most certainly do put a dpi setting in the image headers. Often it is 72 dpi, some cameras use 300 dpi. The reason will be that there is at least some setting that will produce a printable image. Most people will not use a program like AP, or PS to manipulate their images.

I always use the raw image from my camera, and leave that untouched. When I have worked on the image, I will save it as PSD (with PS or) the native file format of AP.  I will make.jpg copies of that image for the purpose I need them for. If I use it in a document, I will set the size in cm, and the dpi setting, and then recalculate the image. For a web image, I will just set the pixel size and recalculate. After all, the dpi setting has no effect for web images.

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All you need to do is to scale the picture to the dimensions you need for print inside the DTP app. In most cases the DPI will be over 300. So, when you output the file to PDF you will have to set (in PDF export pannel) the value of 300 for DPI and everything will be fine.


Dell Inspiron 7559 i7    Windows 10 x64 Pro
Intel Core i7-6700HQ (3.50 GHz, 6M )    16GB Dual Channel DDR3L 1600MHz (8GBx2)    NVIDIA GeForce GTX 960M 4GB GDDR5
1TB HDD + 128 GB SSD Hard drive    UHD (3840 x 2160) Truelife LED - Backlit Touch Display

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Yes, I know. However, if there are many images in a multi-page document, it will dramatically increase the size of the document. So I prefer preparing the images as they should be in the document.

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