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Problem with Resize using resize document in 331

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I'm trying to resize an image using the document resize dialog and there seems to be a probem with the new sampling option.

With the new sampling check selected:

If I just change the PPP value with pixels selected as the units value the pixel values in the uper boxes are changed automatically.

If I select units CM and then change de PPP value,(from 96 to 300)  the CM values are not modified in the upper boxes, 
but after clicking OK in the dialog, I was expecting a file with the CM showed in the upper boxes and 300 DPI

But the result is a 300DPI image with smaller height and widht values that the ones showed in the upper boxes of the change image size dialog.  (No new sampling applied to the image)

 

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Hi both,

Why do you think that changing the DPI should change the CM value? The resize dialogue does what you ask. Let's take an image 72x72px, units in inch @ 72DPI. If you open the resize dialogue and set the units to inches, you will have 1 in x 1in and the DPI value of 72.  If you only modify the DPI, it will not change the size in inches, because that's not what you've asked. You've asked for a 1in x 1in image with a different DPI. Changing this to 144 for example will create a canvas of 1in x 1in @144 DPI, which is 144px x 144 px.

Thanks,

Gabe. 

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Hi Gabriel,

That is exactly the problem, the dialog is changing the CM values with out the user requesting this.

I have the issue in CM but to make it easier I will take your example in Inches. I tried your example using the 1x1 inch value and it works fine, the resize is as you explained.
but I took another file with other values and this is what happens, I changed the values to inches to make it easier to explain here.

I have a document 19.29x10.237 inches at 300 dpi.
I open the dialog and change the dpi to 600 dpi
The final document is:   9.645x5.118inch  600dpi.

As you explained I would have expected to have a 19.29x10.237 inch 600dpi file.

Using 1x1 inch in my test does not make this strange size change. try with diferent file sizes.

(Tested in version Beta 333)

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DPI does nothing for the physical size (inches) of an image. DPI=Dots Per Inch, which is exclusive to print media, not display such as screens. I done a quick screen recording demonstrating this. I can change the DPI clear through the spectrum, and the inch size does not change. However if I set the units to Pixels, then the DPI is really PPI, which is Pixels Per Inch, thus the screen display size changes, not the print size.

 


Affinity Photo 1.7.2.471 ; Affinity Photo Beta 1.7.2.464; Win10 Home Version:1903, Build: 18362.207: Intel Core i7-4770, 3.90GHz, 32GB Ram, Nvidia GTX 645, 3-Internal HDD (1 Crucial MX5000 1TB, 1-Crucial MX5000 500GB, 1-WD 1 TB), 4 External HDD

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I  do not know how to save video but I have attached 3 files with the problem.

Image 1 Open document size window, original image DPI 300 DPI

Image 2 changed resolution form 300 to 600 and clicked change size button.

Image 3 open again the Change document size window.

When I was trying to do this in my test I noticed that this did not happened in a blank document 30x30 cm.

So I opened a random image and there was the problem.
Also If I modify the DPI again from 600 to 300 DPI  the CM value is now preserved.

Will post the 600 to 300 DPI photos in another post to avoid confusion.

1g.jpg

2g.jpg3g.jpg

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The problem did not happened when changing from 600DPI to 300DPI

This is a follow up from the last post just splitted the post in 2 parts to avoid confusion.

Image 1 original DPI 600 DPI   (From the already modified file in the last post)

Image 2 changed resolution form 600 to 300 and clicked change size button.

Image 3 open again the Change document size window.

Now the problem is not there. the CM values where respected.

 

3g.jpg.08fa9cdc7f7759838970f1be62418a3f.jpg5g.jpg.307dfad51652e4c49f2bee5b08890a0b.jpg6g.jpg.c230d2627a0182c07484aa4ca611c8a3.jpg

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