Resize very large images into very small images

[M_alvarez 0]

I have a very large image 5000px x 3500px and I need to make it 870px x 320px for a website banner. 

 

I know I have to crop the image first because the ratios are not the same, but I have tried many ways, even tried to edit the SVG code, and it's just impossible. 

 

The image doesn't look sharp enough. 

 

Is this impossible to do? am I wasting my time? or is someone actually able to resize this much a very large image and keep at least moderate quality? 

 

Thanks!

 

 

[R C-R 2,616]

5 hours ago, M_alvarez said:

Is this impossible to do?

Short answer: yes, it is impossible.

 

Longer answer: ignoring cropping, you are trying to reduce 17.5 million pixels to around 278 thousand pixels, which means every 63 or so pixels of the original has to be replaced with 1 pixel in the smaller version. That does not allow for much detail retention, so unless there are not many fine-scale details in the original, the smaller version is going to look terrible.

[Alfred 3,230]

7 hours ago, M_alvarez said:

The image doesn't look sharp enough.

 

Please forgive me if I’m asking the obvious, but have you tried sharpening it?

 

Getting a usable result is generally much easier when shrinking an image than when enlarging one, since you only have to discard existing pixels instead of creating new ones.

[R C-R 2,616]

8 minutes ago, Alfred said:

Please forgive me if I’m asking the obvious, but have you tried sharpening it?

For such extreme size reductions, the best approach is likely to be simplifying the image first as much as possible, like by painting out fine details or using noise reduction selectively, or whatever else works best to preserve important large scale details & eliminate fine scale ones.

[Alfred 3,230]

2 minutes ago, R C-R said:

For such extreme size reductions, the best approach is likely to be simplifying the image first as much as possible, like by painting out fine details or using noise reduction selectively, or whatever else works best to preserve important large scale details & eliminate fine scale ones.

 

In general, yes. If we could see the actual image we might be able to offer more specific advice.

[M_alvarez 0]

First of all, thank you guys for your replies. 

 

@R C-R I thought this was impossible as well, I had my hopes up. 

 

@alfred absolutely! I attached 2 images - I couldn't upload the original, maybe because it's really big. The original, cropped, and my attempt to resize it to 870px x 320px. 

 

Thanks again! 

[MikeW 1,309]

11 hours ago, M_alvarez said:

I have a very large image 5000px x 3500px and I need to make it 870px x 320px for a website banner. 

 

I know I have to crop the image first because the ratios are not the same, but I have tried many ways, even tried to edit the SVG code, and it's just impossible. 

 

The image doesn't look sharp enough. 

 

Is this impossible to do? am I wasting my time? or is someone actually able to resize this much a very large image and keep at least moderate quality? 

 

Thanks!

 

 

 

Try using Unsharp mask or even sharpening before cropping/resizing. You'll need to experiment once or twice, but use an amount that looks over sharpened. What you will likely need is enough of a value to overcome the size of the image and look, well, sort of bad.

 

Then crop and resize. It will get softer when the resize happens. And you will need to experiment whether bicubic or Lanzcos works better fr you. The below was a first attempt.

 

[Alfred 3,230]

2 hours ago, MikeW said:

And you will need to experiment whether bicubic or Lanczos works better for you.

 

Lanczos usually works better when resizing upwards, and bicubic (or even bilateral) usually works better when resizing downwards, but the rules may be different if you’ve sharpened the image beforehand.

[EZeemering 179]

13 hours ago, Alfred said:

 

Lanczos usually works better when resizing upwards, and bicubic (or even bilateral) usually works better when resizing downwards, but the rules may be different if you’ve sharpened the image beforehand.

 

Hmm I find that lanczos works better for downsizing. I haven't touched bicubic in the last couple of builds tho.

[HVDB Photography 160]

Using a Live Unsharp Mask filter