topic Re: Raw Image Visibility and size. in Camera Software

Raw Image Visibility and size.

Epicuros — Fri, 06 Jul 2018 01:35:40 GMT

I have read several articles in which it is claimed that RAW images are not visible unless converted. However, in DPP software that comes with our EOS camera, we can see raw images even before conversion. If these are the +JPEG images the camera produces how come we process RAW images based on the JPEG images we see? There must be something I am missing. Besides, I noticed that RAW image size is quite smaller than the converted TIFF image size How is this?

Re: Raw Image Visibility and size.

RobertTheFat — Fri, 06 Jul 2018 03:52:45 GMT

@Epicuros wrote:
I have read several articles in which it is claimed that RAW images are not visible unless converted. However, in DPP software that comes with our EOS camera, we can see raw images even before conversion. If these are the +JPEG images the camera produces how come we process RAW images based on the JPEG images we see? There must be something I am missing. Besides, I noticed that RAW image size is quite smaller than the converted TIFF image size How is this?

The commonly repeated assertion that a RAW image can't be displayed is something of an overstatement. It can't be processed by the usual display algorithms, but software can obviously be written to display it, as in DPP. Also, a RAW file customarily contains a small embedded JPEG rendition of itself. Its resolution is too low to be useful in a photo editor, but it can be used to provide a thumbnail display by cataloguing programs like the Windows Explorer.

A TIFF image is large because, unlike a JPEG, it's designed to be "lossless" and very general. TIFF is probably less efficient than it could be, but it's used so little these days that its inefficiency can usually be overlooked.

Re: Raw Image Visibility and size.

Epicuros — Fri, 06 Jul 2018 12:40:35 GMT

Thanks for your prompt response Bob. I understand that most often than not a JPEG thumbnail accompanies the RAW file, but when you process RAW images on DPP you have the possibllity of a full screen image and the editing steps are immediately visible. If we were working on a JPEG image, even one with little loss, how valid would be the processing if what we see is a JPEG and not an original RAW image? I find this difficult to conceive... Further, I quite understand why a TIFF file is larger than a JPEG file, but what I don't understand is why it is bigger than a RAW file... I am not a software nerd, so I may be writing nonsense, but we, old guns will never be fully conversant with new tech. 🙂

Re: Raw Image Visibility and size.

RobertTheFat — Fri, 06 Jul 2018 22:08:12 GMT

@Epicuros wrote:
Thanks for your prompt response Bob. I understand that most often than not a JPEG thumbnail accompanies the RAW file, but when you process RAW images on DPP you have the possibllity of a full screen image and the editing steps are immediately visible. If we were working on a JPEG image, even one with little loss, how valid would be the processing if what we see is a JPEG and not an original RAW image? I find this difficult to conceive... Further, I quite understand why a TIFF file is larger than a JPEG file, but what I don't understand is why it is bigger than a RAW file... I am not a software nerd, so I may be writing nonsense, but we, old guns will never be fully conversant with new tech. 🙂

Don't say that! I'm probably older than you are, and I'm not about to sell us old geezers short.

The reason a TIFF is larger than a RAW file is that a RAW file records the data exactly as it came from the camera, while TIFF has to deal with the fact that its data could have come from any of a variety of RAW formats and must be recorded in a camera-independent form. One consequence is that it must account for higher resolution (and potentially longer data items) than current cameras normally use.

As for editing, keep in mind that when you're editing a picture, you're just looking at a collection of dots on a screen. Whether the underlying image on which you're working is a JPEG, TIFF, RAW file, or something conceptually different is obscured by implementation detail. The photo editor has to try to ensure that "what you see is what you get", but how it does that is ultimately unimportant. If the final result is, say, a JPEG, then that JPEG must be (assuming that the display or print algorithm does its job correctly) a faithful representation of what the camera saw. As long as that's the case, what goes on in the editor itself is like making sausage: you can't see how it's done and probably wouldn't want to.

So when someone tells you that "what you see (when you're editing a RAW file) is actually a JPEG", that assumes that the editor converts the RAW image to JPEG and turns it over to a JPEG processing module for display. With some editors, maybe that is what happens, but it's not a given. And it doesn't matter anyway, as long as what is done is good enough to satisfy your eyes.

Re: Raw Image Visibility and size.

kvbarkley — Fri, 06 Jul 2018 17:39:50 GMT

Actually, the reason the Tiff is larger is that it takes the bayer image from the sensor and converts it to Full RGB. So the RAW file has only 1 color channel, 1/4 red, 1/4 blue and 1/4 green, while the Tiff has 3 full color channels.

Re: Raw Image Visibility and size.

RobertTheFat — Fri, 06 Jul 2018 18:28:50 GMT

@kvbarkley wrote:
Actually, the reason the Tiff is larger is that it takes the bayer image from the sensor and converts it to Full RGB. So the RAW file has only 1 color channel, 1/4 red, 1/4 blue and 1/4 green, while the Tiff has 3 full color channels.

Just what I said! (Although you stated it much more accurately and succinctly.)

Re: Raw Image Visibility and size.

kvbarkley — Fri, 06 Jul 2018 20:58:07 GMT

I messed up anyway! 8^)

Should be 1/2 green.

Re: Raw Image Visibility and size.

Epicuros — Sun, 08 Jul 2018 09:21:57 GMT

Thank you all. The combined answers shed quite a bit of light on my confused brain! Q-)

Re: Raw Image Visibility and size.

ebiggs1 — Tue, 10 Jul 2018 14:28:38 GMT

The big thing to remember is compression. Raw is not compressed. Jpegs are, sometimes severely. It is this compression which actually deletes info from the file to make it smaller that concerns us. Less info = less ability to edit.

Another thing to remember no camera company can agree on exactly what is a Raw file is so no standard exists. Not even among models from the same company!

A Raw file is not effected by any edit you do. Jpegs are permanently altered when edited or even saved for that mater. A Raw file contains two thing besides the raw data. One is a metadata tag and a jpeg for viewing on the cameras LCD. These two tag along files are what is used by your post editor to give you a viewable photo. It is not the actual Raw file however. It does give you a starting point for your edits but you notice you don't save a Raw, you save something else. A tiff or jpg, etc. Plus the metadata tag is updated.

BTW, guys, I use tiff all the time.Lots of good stuff in a tiff.

Re: Raw Image Visibility and size.

Epicuros — Tue, 10 Jul 2018 02:29:16 GMT

Thanks for your response ebiggs1

Re: Raw Image Visibility and size.

ebiggs1 — Tue, 10 Jul 2018 14:41:12 GMT

If you use Adobe ACR to do your edits, you will notice it makes an xmp file for each edited Raw file. That is the tag file that remembers your edits. If you should move the Raw file and not move the xmp tag, all your edits will be lost. If you move or copy the Raw file, you must move or copy the xmp file, too.

Re: Raw Image Visibility and size.

RobertTheFat — Tue, 10 Jul 2018 16:09:26 GMT

@ebiggs1 wrote:
If you use Adobe ACR to do your edits, you will notice it makes an xmp file for each edited Raw file. That is the tag file that remembers your edits. If you should move the Raw file and not move the xmp tag, all your edits will be lost. If you move or copy the Raw file, you must move or copy the xmp file, too.

And in that respect Canon's Digital Photo Professional handles editing better, because it maintains your edits in the RAW file itself, while still allowing them to be changed or discarded. (You can also maintain edits separately in a "recipe" file, but that's not required.)

Re: Raw Image Visibility and size.

ebiggs1 — Tue, 10 Jul 2018 18:44:56 GMT

"... Canon's Digital Photo Professional handles editing better,..."

"Better", not really if you just consider this one approach better the rest of the advantages in LR/ACR far exceed this. Personally, I do not consider it a better way to do it anyway. I keep coming back to this but neither do 99.9% of all professionals in the business.

You like DPP4 and more power to you. I freely admit it works. However, it is not and will not replace LR/ACR or PS.

"recipe" file, but that's not required..." LR/ACR or PS have what is called a 'preset' which can be applied upon import or later whenever. Also, the xmp file can be saved alone and later loaded to apply to any photo or any batch of photos.

You know DPP4 way better than I, but you will have to really dig to find something it does better than LR/ACR or PS. Perhaps you will?

Re: Raw Image Visibility and size.

ebiggs1 — Tue, 10 Jul 2018 18:58:29 GMT

BTW, the xmp file can be handled in several differnt ways.

When a camera Raw image file is processed with Camera Raw, the image settings are stored in one of two places. The Camera Raw database file or a sidecar XMP file. If you choose to save it as a DNG file, the settings are stored in the DNG file itself, but they can be stored in a sidecar XMP file instead, either way.

In addition, you can record the state of an image at any time by creating a snapshot. Snapshots are stored renditions of an image that contain the complete set of edits made up until the time the snapshot is created. By creating snapshots of an image at various times during the editing process, you can easily compare the effects of the adjustments you make. You can also return to an earlier state if you want to use it at another time. Another benefit of snapshots is that you can work from multiple versions of an image without having to duplicate the original.