Recalculate photo

[Juergen S]

Affinity Photo – Recalculate photo

Hello,

I have a problem with the quality of an image recalculation.

I want to resize a PNG logo from 280 px width to 250 px width.

No matter if I choose bilinear or bicubic, the result always looks very bad, i.e. it gets totally blurred.

Unchecking the recalculation box gives the same bad result.

Thank you in advance

Juergen

[John Rostron]

You are scaling your image by 0.893 which does not give the resampling algorithm much leeway. Have you tried Nearest Neighbour? Why do you need to scale it by that amount?

John

[Juergen S]

Hello John,

thank you very much for your spontaneous answer! 😃

So until now I was not even aware that I have to pay attention to something like that. In PS I can enter any value and the result is always absolutely perfect with "Bicubic automatic"!

But I tried it once with 50 percent reduction, so from 280 to 140 px. But the result is the same.

With "Next neighbor" there is no blur, but the image is extremely coarse pixelated. Unfortunately, this is not the way to work!

Translated with www.DeepL.com/Translator (free version)

[John Rostron]

I think that for us to to help you further, you should post your logo (as a file, not a screenshot).

John

[Juergen S]

Okay, thank you for help.

r-m-logo_280.png = Original

r-m-logo_250_afph.png = Affinity Photo bilinear (blurred)

r-m-logo_250_ps.png = Photoshop, sharp as original

[Joachim_L]

250px Affinity Bicubic

[Juergen S]

That looks great!

The question is: Can I make anything wrong or is it caused of my Mac platform? (I see you are working on a pc.)

I also have a similar problem with the conversion of JPGs. For the web, I always use 40 percent quality. That still looks very decent in PS. In Affinity Photo, the artefacts are visibly more and larger.

That is - unfortunately - a reason for me to still use CS6. I would much rather work completely with Affinity Photo. The range of functions alone is not everything, the quality must also be right!

 

[Juergen S]

Mojave 10.14.6 | Mac Pro 3,46 GHz 6-Core Intel Xeon | 48 GB RAM | Radeon RX 580 8 GB | Affinity Photo 1.9.3

[Juergen S]

Sorry for the typos! 😉

[Alfred]

26 minutes ago, Juergen S said:

Sorry for the typos! 😉

To fix typos or make any other corrections, click on the ellipsis in the top right-hand corner of your posted message and choose ‘Edit’ from the menu.

[Juergen S]

Thank you Alfred, that is a nice feature!

[walt.farrell]

2 hours ago, Juergen S said:

I also have a similar problem with the conversion of JPGs. For the web, I always use 40 percent quality. That still looks very decent in PS. In Affinity Photo, the artefacts are visibly more and larger.

It has been mentioned here that PS always applies some sharpening when converting to JPG. Affinity does not. Have you tried applying a small amount of sharpening (or an Unsharp Mask), and see if that helps?

[Juergen S]

Hello Walt,

thank you for your feedback!

Hmm, I don't think so. Sharpening always brings additional artefacts into play and that's exactly what I mean.

The formation of artefacts is less with PS than with AfPh. Here is an example ...
(Enlarge a bit and look for artefacts in contours).

Back to the recalculation of images:

I am glad to see that the blurring effect when recalculating images is not a general problem of AfPh (see Joachim_L), but a specific one on my computer. Then the problem should also be solvable for my configuration. The only question is: How?

Best regards

Jürgen

[Joachim_L]

27 minutes ago, Juergen S said:

The only question is: How?

Good question. I tried some things on my machine ... resize before export (including resizing to whole pixels), resize in the export dialogue, but the outcome was always sharp. As I have no Mac I cannot give you a good advice to solve your problem. Perhaps some Mac users want to join the discussion.

About sharpening bringing artefacts into the image: The last image looks like being saved with a too strong compression. To avoid trial and error you can use the Preview button in the export dialogue to find the best setting.

[Juergen S]

Both images have been converted with exactly 40 percent quality. To match the quality of PS, I have to go to about 70-80 percent in AfPh. Then of course I have an undesirably large file.

Here I currently think that PS has the better algorithms. (A hint to the developers).

Best regards

Jürgen

[loukash]

5 hours ago, Juergen S said:

PS has the better algorithms

PS has different algorithms.
You can't compare them by the exact numbers.
Heck, even Photoshop's Save As… JPEG and Save For Web: JPEG use different algorithms and different scales!

Depending on the source material, you can achieve comparable results in Affinity in terms of compression quality and file size.
The "Lanczos"  resamplers will slightly sharpen, so those are particularly recommendable when downsizing.

From my own earlier comparisions, export quality "60" is about the lowest possible value to prevent the typical ugly artifacts and blur in the reds, and approximately comparable to Photoshop's values "7 (of 12)" (Save As) or "51" (Save For Web). The sweet spot is around 70.
The "Progressive" option will usually additionally reduce the file size without introducing noticeable artifacts.

Use the Preview window in the Export dialog to fine tune.

So, let's compare apples to apples, downsizing a tricky photo from Pexels with lots of reds, no other adjustments used.

• Affinity Photo, Lanczos 3 non-separable (sharpens nicely on downsizing!), quality 78, progressive, file size circa 60 KB
  
   
• Photoshop CS5.1, bicubic "sharper", quality 7 of 12 (Save as JPEG), progressive, file size circa 60 KB
  
   
• Photoshop CS5.1, bicubic "sharper", quality 51 (Save For Web), progressive, file size circa 60 KB
  

 

[loukash]

Back to your original issue:

On 5/25/2021 at 1:33 PM, Juergen S said:

resize a PNG logo from 280 px width to 250 px width

Resized to 250×284 px, left side Affinity, right side PS CS5.1:

^ Looks identical to me.

Caveat:
You may want to unlock the proportions when resizing in Affinity, otherwise it will internally calculate subpixel values, possibly without even displaying that it does so (unless you increase the corresponding decimal places display preferences):

[Juergen S]

Hello Lukás,

Thank you very much!

I have so far proceeded in such a way that I export the image via

File > Export

converted. With this procedure, the option "Progressive" is not even offered to me or I have overlooked it.

In order to follow your recommendations, I am now in the

Export Icon > Export Dialogue Window

dialogue window. Here I can also set a check mark for "progressive". But how do I proceed now? I can't see any option for "Preview" in the window and how do I initiate the export process from there (see screenshot!)?

Kind regards

 

[Juergen S]

Edit:

Under

File > Export

you have to click on the "More"-Option to set the Progressive Marker. 😉 Okay!

[Juergen S]

I have now created a recipe picture with logo in

AfPh with 78 percent, progressive ', Lanczos 3 not separable

and the same image "optimised" in PS with 40(!) percent.

as a JPEG.

Unfortunately, I have to say that I still find the PS image much better. In the logo you can see the difference in the artefact formation very clearly.

The PS image is 97 KB, the AfPh image 175 KB.

[loukash]

Kannst du mal das Ausgangsbild hochladen?

[Juergen S]

Off topic:

@Lucás

Hi Lucas,

I strongly suspect you are from Hungary?

I am an enthusiastic amateur chef, let me say: the Hungarian Mangalitsa pig is the absolute best pig in the world, it is in fact even better than Iberico or Duroc!!! 👍

 

[Joachim_L]

Better zip the image, otherwise the forum software will ruin the original data.

[Juergen S]

Hello Lucás,

kann ich gerne machen ...
I can do that with pleasure ...

backfisch-mit-pommes-frites_2.psd

[Juergen S]

Oh, this advice has been come to late. Here comes the zip ...

backfisch-mit-pommes-frites_2.psd.zip