Image Size - reduction and resampling option choice

[IanfaeAiberdeen]

I'm coming over to Affinity Photo from Photoshop and hit a problem which I had to resolve quickly - that meant reverting to Photoshop because I know how to do it.

 

I regularly require reduced copies of photographs for websites, and with Photoshop I do this with Save For Web and Devices, using Bicubic Sharper as the resampling method.  This option isn't available in Affinity Photo, which offers Nearest Neighbour, Bicubic, Bilinear, Lanczos 3 (separable) and Lanczos 3 (non-separable). I was in a hurry to do one in Affinity Photo, so accepted the default Nearest Neighbour, which produced a dreadful result, full of artefacts even saving as a JPEG 100% quality. I don't normally save in JPEG format (I prefer PNG) but it was a quick fix to replace a file uploaded from my iPad using a crappy (free) resize app which does only JPEG. It was quicker to open the photograph in Photoshop and do it there than to experiment with different settings or even consult the help system, so that job is done.

 

Coming back to the problem, I find that here is zero information in the Affinity Photo help system (that I could find) explaining the different resampling methods and which is best for what kind of resizing. Wikipedia is not a great help, the article on Lanczos resampling being mathematical rather than practical. I have a degree in Physics and the maths isn't a problem, but it's no help in deciding on the most effective method for image reduction for the web. It appears that the Lanczos method introduces ringing artefacts which may give the illusion of sharper edges than bicubic, so one of these methods may be similar to Photoshop's 'bicubic sharper', which I find acceptable for reductions down to 300-400 pixels wide.

 

Can someone explain in simple language which of the methods is most appropriate for my needs? I have a feeling that it is probably one of the Lanczos 3 methods or bicubic but it would be nice to know the ins and outs of each method.

[A_B_C]

Maybe this thread is of interest for you:

 

https://forum.affinity.serif.com/index.php?/topic/9378-what-is-the-difference-between-lanczos-seperable-and-non-seperable/

 

:)

[Chris_K]

Obviously it's a lot more complicated than this, but

 

Nearest neighbour basically fills in the pixels based on those adjacent to it

 

Bilinear adds some interpolation between pixels to produce a smoothing, anti-aliasing effect. This is generally better for enlarging

 

Bicubic sharpens edges, this is usually better for reducing size where detail is normally lost

 

Pixels are passed into an algorithm that averages their color/alpha using sinc functions

 

 

 

So i'd recommend  bicubic for your purposes

[Inspector]

Hi there.   Using Photoshop for years and decided to try Affinity Photo and Designer.  Great software but a big letdown on exporting images in PNG or JPEG.  Results are not perfect like Photoshop.   The default in Photoshop is perfect for saving files no matter what way you export them.  Saved a PNG from Infinity and one from Photoshop.   Difference is very very noticeable.  Even when a PNG file is save from Infinity and imported into Photoshop, image leave a lot to be desired.  Every thing in Infinity works well and images on screen are sharp but Im afraid that that is were it ends.   Shall continue to use Photoshop until this is resolved as cannot take chances on final images being inconsistent.  

[lrjdesign]

Arghhh. i'm going to have to go back to photoshop too... Can't get crisp text jpeg's or png's in affinity. I hadn't noticed until a client did

 

[walt.farrell]

26 minutes ago, lrjdesign said:

Arghhh. i'm going to have to go back to photoshop too... Can't get crisp text jpeg's or png's in affinity. I hadn't noticed until a client did

 

Perhaps you should describe the process you're using, and provide some sample files so we can see if there's something that will give you better results.