Image resolution changes when creating focus merge.

[MichaelG]

Affinity Photo V1.7.1.404 on Windows 10.

This problem was reported in another thread against Affinity Photo V1.6. However that thread is now locked, and I have encountered the problem with the current version.

In the Affinity Photo Workbook section 7 of Chapter 3, entitled "Mother of Millions", describes how to create a focus merge. I have encountered the problem using the sample images supplied to accompany this section.

There are a total of 41 sample JPEG images supplied for this exercise. Each image is 6000 x 4000 pixels at 240dpi. This would give a print size of 25.0" x 16.7" without resampling. If I go through the steps in the workbook and create a focus merge, the resulting image is 6000 x 4000 pixels at 96dpi. Therefore the native resolution of the source images has been changed. In fact, the same problem occurs when merging any two of the source images. If just one of the JPEG images is opened, then the native resolution of 240dpi is maintained as expected.

In addition, the supplied file mother_of_millions.afphoto has a resolution of 96dpi.

I realize that I can  change the resolution back to 240dpi by using Document > Resize Document... option and switch Resample off. However my expectation is that, when merging a number of images with identical dimensions and resolution, then the original resolution of the images is maintained. (This is what happens when creating a merged images with Photoshop CS6). Is this expectation reasonable?

Of course I don't know if this is the expected behaviour or not. However the earlier thread implied that on versions of Affinity Photo prior to 1.6, this did not happen.

I won't bother uploading any supporting images as I'm assuming that the development team has all the material required to reproduce this problem. Please let me know if you need any further information.

Thanks,
Mike.

 

[Gabe]

Hi @MichaelG,

Sorry for the delayed reply. This is not technically a bug, but I will log it as an improvement. DPI value is only a printing attribute and has nothing to do with the actual resolution in pixels of the image. You can have 1 or 1000 dpi for the same 6000 x 4000 image, and it will still have the same number of pixels. DPI will just work our how many Dots Per Inch your printer will use. That's all. 

On 8/7/2019 at 12:05 PM, MichaelG said:

If I go through the steps in the workbook and create a focus merge, the resulting image is 6000 x 4000 pixels at 96dpi. Therefore the native resolution of the source images has been changed. In fact, the same problem occurs when merging any two of the source images. If just one of the JPEG images is opened, then the native resolution of 240dpi is maintained as expected.

The resolution has not changed. It's still 6k x 4k. 

On 8/7/2019 at 12:05 PM, MichaelG said:

This problem was reported in another thread against Affinity Photo V1.6. However that thread is now locked, and I have encountered the problem with the current version.

On 8/7/2019 at 12:05 PM, MichaelG said:

Of course I don't know if this is the expected behaviour or not. However the earlier thread implied that on versions of Affinity Photo prior to 1.6, this did not happen.

When you mention other threads, it's better if you link us to them. Otherwise, we do not know which thread it is.  I tested this in 1.6 and the output has got 96dpi, the same as 1.7.

Thanks,

Gabe.