Export in TIFF without resampling?

[GrandSchtroumpf]

I have to manage scientific pictures in TIFF format. I can merge two pictures as panorama or side to side, but when I want to save or export the result in ont larger TIFF, I don't want to resample, I want to keep the exact high quality if the initial pictures. How to do this ?

 

Thanks

[Dan C]

Hi GrandSchtroumpf

When exporting to a raster format, such as TIFF, Affinity has to rasterise the page and all layers into one file, which requires resampling of some type. If you're looking to retain as much detail as possible, make sure your quality slider is set to 100% and set the resampler to Lanczos 3 Separable. 

I hope this helps!

[walt.farrell]

1 hour ago, Dan C said:

When exporting to a raster format, such as TIFF, Affinity has to rasterise the page and all layers into one file, which requires resampling of some type.

Resampling occurs even if the output size matches the document size? Why would it be necessary in that case, especially if one already has raster layers?

[Dan C]

I'm looking to gain more information from our devs here, as I passed on the response from our QA team so I'm unable to answer the above currently - apologies!

I'll update you here with any info I'm provided  

[Fixx]

I am assuming you use Photo. When you select "export" the default pixel size is the exact pixel dimensions of your document. No resampling happens.

[GrandSchtroumpf]

You are right, i use Photo.

Do you mean that despict that the export process in TIFF ask me to choose a resampling process, it doesn’t apply  if I dont’t modify the pizel size of my document ?

[walt.farrell]

11 minutes ago, GrandSchtroumpf said:

You are right, i use Photo.

Do you mean that despict that the export process in TIFF ask me to choose a resampling process, it doesn’t apply  if I dont’t modify the pizel size of my document ?

It shouldn't. That's why I asked Dan to clarify his answer.

[Fixx]

It should not ask to select resample method. Is there something in the work flow which might cause this?

[lacerto]

(...)

[Dan C]

I just wanted to update this thread to say I have not forgotten - due to the 1.8 rush the priority for this information has been dropped for more pressing matters, but I will still be certain to respond as soon as I have a clear answer. Apologies for the delay!

[lepr]

On 2/26/2020 at 11:12 PM, GrandSchtroumpf said:

You are right, i use Photo.

Do you mean that despict that the export process in TIFF ask me to choose a resampling process, it doesn’t apply  if I dont’t modify the pizel size of my document ?

Even when exporting the document at full scale, the resampling method will be employed for any Image or Pixel object in the document that has been scaled, rotated or is simply misaligned with the document pixel grid.

[GrandSchtroumpf]

this is a clear answer, thanks.

 

What would be the most acurate ( or less disturbing) resampling method when I don’t change the pixel size of the document ?

[Fixx]

1 hour ago, anon2 said:

resampling method will be employed for any Image or Pixel object in the document that has been scaled, rotated or is simply misaligned

True, it does that. Pixel dimensions stay as they are in document canvas (unless you change them) but you may change resampling method. I think that was not available n previous versions unless you changes size. This is better.

1 hour ago, GrandSchtroumpf said:

What would be the most acurate ( or less disturbing) resampling method

I would use bicubic (which is softer) or Lanczos (which is sharper). I think nearest neighbour and bilinear are too coarse. Lanczos non-separable may be even sharper than separable I presume. Notice that sharper is not always better as there may appear artifacts.

[nur]

I think there should be an option for not resampling when exporting.

This "bug" makes Affinity products non-usable for many of my purposes.

I do digital art with Procreate, and I like to finish my artwork in another software in a PC for final color and layout adjustments. I really like that Procreate can export in .psd and that Affinity can read it, so I can edit individual layers later.

One of the reasons for this workflow is that the size of the document in Procreate is limited by the ipad resources. So I normally work with the smaller canvas possible to gain the highest dpi/number of layers possible. Then later, in the PC I like to put the artwork in a bigger canvas so I add some margins to the piece and the signature and make the final layout. However, when exporting everything is ruined because Affinity forces me to do a resampling and I can notice artifacts in the final file. I thought on exporting as .psd and do the final export to image with Gimp (which allows me to export without resampling) but Affinity forces me to do a resampling even for saving as .psd.

There are other occassions when I have to do artwork for printing but I don't know at the beggining the exact final print size. In these cases I produce it with an overkill resolution (450 dpi for example) for some guess size. Later, I can scale the artwork to bigger physical sizes by reducing the dpi up to 300 without affecting the number of pixels (so no resampling needed). For this, Affinity Designer and Gimp are also usefull as you can change the dpi of the artwork without resampling and see how the size of the artwork inside the canvas changes when changing resolution and preserving the amount of pixels. The problem is, again, when exporting, because Affinity forces me to do a resampling while Gimp not.

For now, I have to work everything inside Procreate merging layers to gain memory or Gimp. But I would like this to be fixed so I can make the best of my Affinity suite.

Edited May 19, 2022 by nur

[NotMyFault]

3 hours ago, nur said:

think there should be an option for not resampling when exporting.

This "bug" makes Affinity products non-usable for many of my purposes.

 

This might be a mis-understanding. 

1.  If your export dimensions are identical to canvas size, resampling will not change image quality in any negative way. The only catch: All Affinity Apps might show misleading rendering, and exported images may look different in some aspects. If you "merge visible" just before export, you get an (almost) perfect preview of the export.
2. As your document may have multiple layers, and all can have different DPI, rotation, skew etc, the process of resample is technically required and unavailable (when exporting to bitmap formats).
3. Actually, whenever you are viewing a file in Affinity, it will be resampled continuously to be rendered on screen. There is no way to view a file without resampling.
4. On iPad, you are bound to "bilinear" resampling (while viewing). for export, you can choose the method.
5. On Desktop, you can choose between bilinear and nearest neighbour for viewing.

Do you have any example document showing the assumed issue (quality change by resample)?

Do you have the same workflow in e.g. GIMP, showing the assumed difference?

 

Please use a simple example, reduced as much as possible.

3 hours ago, nur said:

The problem is, again, when exporting, because Affinity forces me to do a resampling while Gimp not.

When you export in GIMP, you will use a pixel size, and DPI. You can create the exact same result in Photo / Designer. As long as the pixel size stays constant, there is no change in resolution, and no negative effects by "resampling".