uws Loc: nyc

Most Leica cameras have a feature whereby you can crop a photo in camera but only as a JPG. The camera of course can save both the RAW file which won't be cropped as well as the the JPG. Is there any difference in terms of image quality using one method vs the other?

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

If you crop the JPG it will contain less megapixels than the uncropped RAW file. And, you have more control in post processing with the RAW file. When you say image quality, I am going to interpret image quality as overall sharpness, and no, there would be no difference in sharpness between a cropped JPG and an uncropped RAW file.

petrochemist Loc: UK

I'd expect them to be the same, but it is possible to use interpolation to regain pixels, if one or other of your options does this there could be a difference.

BebuLamar

One thing I can see is that when you crop in post you don't have to retain exactly the center portion of the image.

LFingar Loc: Claverack, NY

Cropping in-camera or cropping while editing have no effect on IQ. Only the size of the photo changes. If you crop a photo and then blow it up the IQ will eventually suffer, but, it will be the same for both.

zug55 Loc: Naivasha, Kenya, and Austin, Texas

I find it impossible to get a good sense of what the image is all about and how to make it better in-camera. I see thing on the big screen that I don't in-camera, and I only develop a full understanding of the image on the big screen. I often do small crops to balance an image better, which I could not do in camera. I don't even delete images in-camera because I want to see it on the big screen it first before I edit or discard it.

JerseyT

One of the ways JPEG achieves compression is by discarding high spatial frequency info. So I would expect that a JPEG would be inherently less sharp than a RAW. But you may not be able to see it in ordinary usage.

bleirer

I don't understand what you mean by high spatial frequency?

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

Yeah, me too. What the heck is spatial frequency?

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

Pardon, but a RAW image and a JPEG image have the same spatial frequency sharpness.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

No they don't . . .

First off, raw files are not image files, and therefore have no spatial frequency sharpness. Only the resulting converted images do. And there is no question that an uncompressed tiff or psd contains more sharpness than a compressed jpeg. In similar fashion, a high quality jpeg (with minimal compression) has more sharpness than one that is highly compressed.

Second, JerseyT was spot on. Lossy jpeg compression (the only one we have that is universally accepted) affects spatial frequency through the mechanism of quantization.

https://en.wikipedia.org/wiki/JPEG

I'm surprised you didn't know that.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Since the camera only crops the jpeg and not the raw file, you have options with the raw file to retain detail and texture that are lost once the jpeg is processed. Jpeg picture controls - Nikon-speak for sharpening, contrast, saturation, etc - are lossy by nature - in other words, once you apply them unneeded data is discarded and those adjustments cannot be reversed. Besides camera adjustments tend to be pretty ham-handed and coarse.

However, once you edit a raw file you have the option to convert it to an uncompressed format - psd and tiff being the most popular - and you can make adjustments with greater range and granularity than what is possible with a camera-generated jpeg.

But this is pretty theoretical, and the image has to have a ton of fine detail to be able to see this difference.

In a Nikon, when you select a smaller crop factor, the crop is applied first to the raw file - so naturally, jpegs end up being cropped as well.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

So sorry, both have the same sharpness. So sorry, your statement is so wrong that it does not require any more than, YOUR WRONG.

TriX Loc: Raleigh, NC

“JPEG uses a lossy form of compression based on the discrete cosine transform (DCT). This mathematical operation converts each frame/field of the video source from the spatial (2D) domain into the frequency domain (a.k.a. transform domain). A perceptual model based loosely on the human psychovisual system discards high-frequency information, i.e. sharp transitions in intensity, and color hue. In the transform domain, the process of reducing information is called quantization. In simpler terms, quantization is a method for optimally reducing a large number scale (with different occurrences of each number) into a smaller one, and the transform-domain is a convenient representation of the image because the high-frequency coefficients, which contribute less to the overall picture than other coefficients, are characteristically small-values with high compressibility. The quantized coefficients are then sequenced and losslessly packed into the output bitstream. Nearly all software implementations of JPEG permit user control over the compression ratio (as well as other optional parameters), allowing the user to trade off picture-quality for smaller file size. In embedded applications (such as miniDV, which uses a similar DCT-compression scheme), the parameters are pre-selected and fixed for the application.

The compression method is usually lossy, meaning that some original image information is lost and cannot be restored, possibly affecting image quality. There is an optional lossless mode defined in the JPEG standard. However, this mode is not widely supported in products.”

Source: Wiki

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Cognitive Dissonance, coupled with a dose of narcissism can be a serious handicap when confronted with facts, huh?