Resizing Issue?

[mike goldberg]

Hi... Recent post of my M2 was Resized to 640 x 480... otherwise the posted photo was larger than life size Leica. Tho' I'm familiar with Pshop & PS Pro 8, I use the excellent & free Irfanview v 3.99 for Resizing & lite photo editing.

PROBLEM: When I go down to the smaller sizes, sometimes the image loses sharpness and begins to 'break up.' FEEDBACK WELCOME... Several different sizes of the attached shot of the M2 were done, until one looked right. :bang:
Thanks, mike

 

[jlw]

This always happens when you resize to a large extent. Resizing an image to make it smaller is a process of "downsampling" it -- the values of several adjacent pixels are averaged together, then they're discarded and replaced by a single pixel with the averaged value. It's the process of replacing several pixels with one pixel that makes the image smaller.

That averaging process is a good thing in some ways -- it smooths out the appearance of grain and noise, for example. But it also smooths out details that you'd rather have remain crisp.

That's why it's pretty much standard procedure to apply a slight amount of sharpening to an image after downsampling it; this restores some of the appearance of crispness. There are various approaches to doing this, but I like Photoshop's "Smart Sharpen" filter. It makes details look crisper in a very natural way, without much risk of exaggerating grain and noise, and it's easy to use.

 

[mike goldberg]

Photoshop's "Smart Sharpen" filter. It makes details look crisper in a very natural way, without much risk of exaggerating grain and noise...

THANKS jlw, and thanks to whomever moved my cheese... ah, Post to Darkroom where it belongs. mike 🙂

 

[MichaelB]

If you would like to have more control over the result than maybe you want to try this. It is just an example to give you the idea. If the original is about 1500 pixels wide and you want it to be 800 wide than resize it to 1000 pixel and use "unsharp mask" to get it to the point or a little over the point you want it to be an resize it to the desired value of 800 without sharpening it again. It will look more "natural" this way. Maybe you want to do it in three or more steps. So maybe resize 1500 to 1200 with "unsharp mask", 1200 to 900 again with "unsharp mask" and then the fnal resize to 800 without the sharpening. Play around a little and you will find the way that best fits your taste. Have fun!