Shade of a circle

[GIOVANNI ACANFORA]

Come posso creare una tonalità rotonda, con un colore centrale che sfuma verso un bordo bianco sfumato?
Ho provato diverse impostazioni (ellisse, conica), ma non sono riuscito a trovare la soluzione giusta.

Si veda l'immagine allegata.

[Oufti]

You could select your ellipse and apply a Gaussian Blur layer FX:

[NotMyFault]

The gradient is quite complex. 

1. use image as reference
2. add a rectangle or ellipse shape
3. Set fill to gradient and radial
4. deactivate rectangle temporarily 
5. set left node to center. Sample color from source file.
6. set right node near edge. Sample color.
7. activate layer.

the result is very similar to source, but there are visible differences. To match more strict, add two more nodes and sample colors.

The difference analyses shows source file has some color and blocky artifacts which seem part of the artwork, not just jpeg artifacts.

 

[R C-R]

I'm probably misunderstanding what the OP wants, but couldn't this be done with an ellipse with the Gradient tool set to Radial, something like this gradiated elipse.afphoto

[carl123]

Does it have to be vector only?

 

[NotMyFault]

I think a detail most replies miss is that it is not just a smooth gradient. Just the opposite, the image has a specific blockiness which is faint and overlooked easily, but when you are able to spot it it makes the fascination. I will dig deeper to analyse this. In the moment I have the assumption that the gamma curve of the red channel was manipulated, either intentionally or when somebody converted the document or a color profile was broke.

Update:

The blockiness is more likely to be jpeg compression artifacts in the red channel. Those values are mostly in the upper range only 10% shy of 1.0. due to 8 bit channel depth there are only about 3 bit or 8 different color values in use causing banding. A grid of 8px shows those artifacts perfectly match 8x8 px blocks. 

[GIOVANNI ACANFORA]

3 hours ago, carl123 said:

Deve essere solo vettoriale?

 

Yes online vectorial

[thomaso]

12 hours ago, GIOVANNI ACANFORA said:

Si veda l'immagine allegata.

• Does your sample show the desired result – or is it what you achieved with a gradient in Affinity but don't like + want to change?

Since your "pink-shade.jpg" as any uploaded JPG got recompressed by the forums software:
• Can you upload the 'original' file as ZIP + let us know if the image has been scaled and/or resampled before?

10 hours ago, NotMyFault said:

The difference analyses shows source file has some color and blocky artifacts which seem part of the artwork, not just jpeg artifacts.

What makes you think that the visible blocky artefacts are indeed desired ("by design";•), especially if the desired result should be…

1 hour ago, GIOVANNI ACANFORA said:

online vectorial

…?  whereby 'online'/'vector' and 'blocky artifact' could be rather contradictory.

• What file type do you finally want to use for the image, @GIOVANNI ACANFORA?

Here's a example with a transparency, not a colour gradient:

[GIOVANNI ACANFORA]

Can You tell me the procedure You have made in this exemple? Thanks

[thomaso]

1. Apply the most intense pink as Fill Colour (not gradient).

2. Use the Transparency Tool + additional nodes (in my example: 2) and adjust their opacity + position + midpoint  (either with only the popup dialog (top right left) and/or with the mouse directly on the graphic.

Edited April 18 by thomaso
corr.: right > left

[GIOVANNI ACANFORA]

Thanks very much!