Cant get my head round Document Resize?!

[Nazario]

Hi, Ive been using Affinity since the very beginning on and off and now that the full suite is pretty much ready for prime time is time for me to take these apps seriously and start to implement them into my workflow at work. Theres one thing that is stopping me though and its Document Resize in Photo.

In Photoshop if I increase the resolution the size of the image shrinks because I'm basically cramming more pixels into 1 inch. That makes perfect sense to me. In Affinity Photo if i choose to increase the resolution the image size also increases which is the opposite of what i expect and therefore is not actually increasing the resolution its just making the image bigger which infact is lowering the resolution.

Can someone please explain how Affinity resizes/resamples things as I'm completely stumped and I've been using Photoshop and explaining resolution, dpi etc to clients for years but this has me completely stumped.

Basically if i have an image at 10x6cm at 150ppi how do i make it 5x3 @ 300ppi?

[AffinityJules]

This might help

 

[John Rostron]

I would guess that you have your default units as cm. Try this on a 10 by 6cm document at 150dpi:

1. Select Document > Resize.
2. Change the units to pixels.
3. Change the resolution to 300dpi
4. Do not tick Resample.
5. Click OK.

Your document should still retain the original size in pixels, but this should map to 5 by 3cm at 300dpi.

John

 

[Nazario]

The video doesn't help me Ive watched it.

John the pixel dimensions increase which is what is confusing me? Note the pixel dimensions remain same in photoshop but increase in Affinity (top left).

 

[John Rostron]

You are right. I applied a change from 150 to 300ppi on a document and the pixel sizes remained the same, as expected.

I then repeated the process (150 to 300) setting the units to centimetres, and the size in centimetres remained the same.

There has been problems in the past with this, but I thought that it had been fixed. I was using the new 1.7 version.

John

 

[Nazario]

Im using new 1.7 too but I've had the issue right from the early betas. I just thought it was me being stupid and not understanding Affinity's implementation. Basically its just adding pixels to the document which is essentially upscaling which in effect is reducing the resolution technically if i'm not mistaken?

This is the main reason why I've not fully adopted Affinity Photo yet as I can't guarantee the resolution of imagery.

[John Rostron]

50 minutes ago, Nazario said:

 Basically its just adding pixels to the document which is essentially upscaling .

Affinity will not change the number of pixels if you have Resample unticked. In this case the dimensions are greyed out, indicating that they cannot be changed. It will upsize or downsize if Resample is ticked. 

John

[Nazario]

It shouldn't but it is. Look at the top left of the Affinity screenshots. Its just adding pixels, even the file size goes up. Surely the print size i.e. 10cm should come down if the resolution is upped?

[John Rostron]

On my Windows box, the pixel count remains the same, but it doesn't on yours. I suggest that you submit it as a bug report.

John

[Nazario]

OK. Thanks.

[R C-R]

On 6/6/2019 at 12:51 PM, Nazario said:

It shouldn't but it is. Look at the top left of the Affinity screenshots. Its just adding pixels, even the file size goes up. Surely the print size i.e. 10cm should come down if the resolution is upped?

This is very weird: I got the same results you did ... once. Now I can't get it to do the same thing again, even on the same file that quadrupled the pixels when I doubled the DPI the first time I opened it.

I have since tried a variety of afphoto, png, & jpg files, some that were originally saved from the 1.7 beta & some not, & some with multiple layers and/or live filters ... but now it all works as expected.

[Petar Petrenko]

I found Photo's "Document Resize" rather confusing. IMO they should do it exactly the same Photoshop's one. That is the only reason I still use Photoshop.

[Nazario]

6 hours ago, R C-R said:

This is very weird: I got the same results you did ... once. Now I can't get it to do the same thing again, even on the same file that quadrupled the pixels when I doubled the DPI the first time I opened it.

Actually I have noticed it is very inconsistent. It works but VERY rarely. Most times it simply increases the document size. Im glad its not just me being daft. Since the Beta version Ive had this problem and just thought it was me not understanding how Affinity are implementing it. I have to use Photoshop to check files are correct so then I simply end up just using Photoshop.

27 minutes ago, Petar Petrenko said:

I found Photo's "Document Resize" rather confusing. IMO they should do it exactly the same Photoshop's one. That is the only reason I still use Photoshop.

I agree. You should be able to see the pixel dimensions alongside the print size so you can tell right away what's actually happening. Its daft having to set the units to pixels then open resize again set the units to centimetres just to check that its done what you wanted it to do. In my case it rarely does.

As much as I love Affinity's products there are a few illogical decisions on a few items that just don't make sense and slow down your workflow. The eyedropper implementation and the tab sequence in the transform window two good examples. It tabs from X position to Width to Y position to Height. Whats all that about?! Anyway im getting off topic in my own thread lol.

[Nazario]

So I've done some further testing on this and it seems that the Resample tick box simply doesn't actually do anything! 

I had a 100x50mm image at 300dpi (1200x600px) and reduced the dpi to 150 with resample turned ON. Thus one would expect the result to be an image at 100x50mm at 150dpi (600x300px) and this is what happens.

With resample turned OFF on the same image one would expect the result to be an image at 200x100mm at 150dpi (1200x600px).

Affinity's result was 100x50mm @ 150dpi (600x300px) the exact same as if Resample was ON.

Im using 1.7.0 but this bug has been prevalent right from the early beta's.

[davemike]

The "Resize Document" procedure has been intentionally designed this way, and it is not considered to be a bug. Unfortunately there is is a huge misconception and misunderstanding on the behalf of the Affinity Photo team, regarding necessary functions required by photo editors and designers. We need to be able to change size versus resolution, while we make the decisions of what we aim for, but the application should make the necessary calculations, Photoshop "Resize Document" has had it right for many years, I think that Affinity should have realized this and tried to produce similar results, it was clear from the 1st A.P. that they got it wrong, and now they are continuing to develop the app based on the same mistake. (the crop tool also suffers in part from the same fundamental flaw).  Please re-think the approach based on functionality, flexibility, accuracy, user-friendliness. BTW Some of my associates (and probably many more) are still using Photoshop just for resizing documents (and cropping) while using Affinity photo for the rest of the job. I am not sure that this is the best place to post this request, perhaps future requests?

Edited June 11, 2019 by davemike
corrected should make the necessary calculations

[Nazario]

Please can you explain the logic behind it for me then as no one seems to respond from Affinity even though I've private messaged people and made numerous threads about this. Im certain i saw a video from Affinity that states "Dpi is a physical measurement" but the logic being suggested is that Affinity don't actually see it as such. Im so confused as to how they implement it.

I certainly do end up taking images into Photoshop to resize but then i just end up staying there so until this is sorted Im probably going to end up just using Adobe stuff unfortunately. Even though I'm desperate to escape.

[Petar Petrenko]

13 minutes ago, davemike said:

The "Resize Document" procedure has been intentionally designed this way, and it is not considered to be a bug.

Nobody say it's a bug. Just a bad implementation of PS's "Image Size".

[Nazario]

1 minute ago, Petar Petrenko said:

Nobody say it's a bug. Just a bad implementation of PS's "Canvas Size".

But Canvas size has nothing to do with resolution?!

[Petar Petrenko]

14 minutes ago, davemike said:

BTW Some of my associates (and probably many more) are still using Photoshop just for resizing documents (and cropping) while using Affinity photo for the rest of the job.

Same as me.

[Petar Petrenko]

Just now, Nazario said:

But Canvas size has nothing to do with resolution?!

Sorry, I've made a mistake and I corrected it.

[Nazario]

1 minute ago, Petar Petrenko said:

Sorry, I've made a mistake and I corrected it.

Phew, I was a whole other level of confused for a minute haha.

[Petar Petrenko]

Just now, Nazario said:

Phew, I was a whole other level of confused for a minute haha.

What could I do. You were so fast. Just as Doc Holliday.

[Nazario]

1 hour ago, Petar Petrenko said:

What could I do. You were so fast. Just as Doc Holliday.

This is funny

[R C-R]

10 hours ago, Nazario said:

So I've done some further testing on this and it seems that the Resample tick box simply doesn't actually do anything! 

I had a 100x50mm image at 300dpi (1200x600px) and reduced the dpi to 150 with resample turned ON. Thus one would expect the result to be an image at 100x50mm at 150dpi (600x300px) and this is what happens.

With resample turned OFF on the same image one would expect the result to be an image at 200x100mm at 150dpi (1200x600px).

Affinity's result was 100x50mm @ 150dpi (600x300px) the exact same as if Resample was ON.

Im using 1.7.0 but this bug has been prevalent right from the early beta's.

For whatever reason, I cannot duplicate your second result -- when I choose "Resize Document..." from the Affinity Photo "Document" menu & untick the Resample box, reducing the DPI by ½ doubles the width & height of the document, just as expected.

I tested using documents set to metric, imperial, typographical, & pixel units, & verified the results by checking the Ruler display & the size of a layer that filled the document side-to-side & top-to-bottom exactly, like with this 300 dpi Resample test.afphoto file. It was created in the 1.7 Mac version of Affinity Photo because I no longer have a 1.6.x version installed on my Mac, but "Resize Document..." has always worked this way for me, including with older 1.6.x versions.

It might be worth testing with this file to see if the results are the same or different from mine.

BTW, you may wonder why my file is only 1181x590 px instead of 1200x600 px. The reason for that is a bit complicated, but basically it is because in the Affinity apps DPI is based on the so-called "desktop publishing point" (a.k.a. the "Postscript point"), a typographical measurement unit. This results in the metrication of 300 DPI (dots/inch) to approximately 118 dpcm (dots/cm). So for example, when entering 100 mm for the width & 50 mm for the height of a new Affinity document, to 2 decimal place precision that becomes 99.99x49.95 mm, or exactly 1181x590 px.

Arguably, Serif could have based DPI on one of at least five (!!!) other typographical point measurement units, or included options to use a different one, but for good or bad they went with the Postscript point version, probably because it is so common in America & Britain.

[Nazario]

I still have the problem even with your file. It happens across the 3 different Macs!!! I simply can't use Photo and no one at Affinity is getting back to me. Its ridiculous. It IS a bug but Im also struggling to comprehend their implementation on resizing/resampling. Their method seems to actually change the data in the image by adding pixels for increasing resolution and removing pixels to lower it. That in effect is destroying the integrity if the image and should not be happening. All the data that is required is already within the image its just the meta data that needs amending to say its now 'Xmm' x 'Xmm' @ 300 dpi.

I acknowledge your info about the pixel dimensions being different to mine. I rounded them out to make it a little easier for the post.

I simply can't use the app until its fixed and I'm seriously considering a refund now which I'm very reluctant to do.