Resize for crop?

[Paresh]

Hi - Just a basic question about cropping: Do i need to resize an image (ie make it larger) before cropping to retain best quality? Thanks.

[Manfred M]

As with many things in photography, the correct answer is "it depends".

The resizing you are referring to is called "upsampling" and the software has to create data through an interpolation process handle the larger size. Different software can be give you better (or worse) results, depending on the internal algorithms used. Software line OnOne's Perfect Resize does a fairly good job upsampling. Versions of Photoshop prior to CS6 were pretty horrible and I would not use them for upsampling any more than around 30%, but Adobe rewrote the algorithm and I find the results of the newer versions indistiguishable from what Perfect Resize does. I can't say how other software performs.

Your final output device plays a part here too. If you have a 24MP camera and you are planning to display it on a standard computer screen (say 1920 x 1080 resolution), that works out to about 2MP, so you can throw away a lot of your camera data without any serious implications before resolution gets impacted.

So as I said in the beginning, "it depends".

[Paresh]

thanks! It's never simple

[DanK]

I'd start with Manfred's second paragraph: the resolution you start with and the resolution you need. If your crop will leave you with more pixels than you need for a given output device, then there is no reason to upsample at all. You will just degrade the image by doing so.

If you do need more pixels than the crop leaves you with, then your question arises: is it better to upsample before or after cropping? I'd have to look more at the algorithm used for upsampling in your particular software, but my guess it that it will make no difference at all, since I would expect the software to work on very small regions in interpolating pixels.

[Dave Humphries]

I absolutely agree with Dan's point clarifying/expanding upon Manfred's words (with which I also agree).

What will make a difference Paresh, is that you should "output sharpen" for the resolution and/or size the image will be viewed (complicated by viewing distance).

Perhaps tell us the context, with some typical numbers and what the intended output will be, so we're not all guessing?

Cheers, Dave

[Paresh]

thanks for the astute posts...I'm over my head here & need to do more study in order to give intelligent responses to yr advice. i shoot raw & probably won't go beyond posting on the web & to internet gallaries like Flikr. I'm currently using Capture One for pp which came with my camera.

[Manfred M]

thanks for the astute posts...I'm over my head here & need to do more study in order to give intelligent responses to yr advice. i shoot raw & probably won't go beyond posting on the web & to internet gallaries like Flikr. I'm currently using Capture One for pp which came with my camera.

That suggests to me that you are shooting either a Sony or a Phase One camera, as these are the only two I am aware of that ship with Capture One.

If you are shooting raw, you have to make some of the adjustments that your camera does automatically, when shooting jpeg; contrast and sharpening. The editing capabilities of Capture One are more or less along the lines of what Adobe Lightroom does, but based on industry standard compliance with ICC profiles.

[Paresh]

right I have a sony camera. I shoot raw + jpeg & am still finding my workflow.