Importance of Optical Zoom

[Dee]

Thanks Chris for posting that! I was searching for my printout cheat sheet I saved from one of your previous posts so I'd get all the steps in the right order. I totally ruined two dive trips worth of photos out of ignorance in saving photos.

Would you mind posting this info in the Tips and Techniques forum above? It's valuable information that everyone needs to learn.

 

[KrustyTheClownFish]

My impression was that RAW format is more than just the absence of JPEG compression. RAW also avoids many of the signal processing operations performed on the imaging pipeline by the camera, such as white balance and others (see http://focus.ti.com/lit/an/spra651/spra651.pdf for a nice white paper). So if you use RAW you can then have full control over the image in your postprocessing in the computer.

RAW format is uncompressed image data. Most digital cameras store data in the JPEG format by default. JPEG loses data to get higher compression rates. Usually this loss is not noticable unless the image is magnified greatly. Saving in RAW format will prevent the data loss at the expense of storage.

 

[OCdiving Deb]

IF YOU DO NOT SHOOT RAW DO NOT MODIFY AND SAVE IMAGES AS JPEGS!!!!!!!!!!!!

1. Always keep all original jpegs, burn two cds, these are your negatives
2. Pick your keepers and save as PSDs or a similar (nearly) lossless format
3. Make all changes to the PSD
4. At the end, after you are all done with EVERYTHING.... save the PSD (so you have a nice version of your altered image)
5. finally, from the PSD, resize for web, or save fr web, or resize and add copyright, whatever web version you are going to present, then SAVE AS a jpeg (note - merely saving a PSD as a jpeg and then resizing it results in a loss)

ChrisM,

This is great info... We need you at our SoCal Oly User Group meetings!! Talk to Sapphire, please! (And I hope to meet you Saturday at the Scuba Show or Casino Night)

 

[archman]

According to all the junk I read from the Mars rovers (which use RAW graphics files), this file type most certainly uses compression algorithms, but unlike JPG's, there's no degradation of quality. That's the whole allure of it over TIF's.

 

[miketsp]

The Olympus C750 has 4 megapixels but 10x optical. What should be my priorities? -Jasmine

Depends on whether or not you want to specialise in shots of Conger Eel tonsils....

 

[ChrisM]

According to all the junk I read from the Mars rovers (which use RAW graphics files), this file type most certainly uses compression algorithms, but unlike JPG's, there's no degradation of quality. That's the whole allure of it over TIF's

Yeah, there was a discussion about this over at DDNet whether RAW (or maybe it was a particular manufacturer?) wasn't really 100% RAW ........

My impression was that RAW format is more than just the absence of JPEG compression. RAW also avoids many of the signal processing operations performed on the imaging pipeline by the camera, such as white balance and others (see http://focus.ti.com/lit/an/spra651/spra651.pdf for a nice white paper). So if you use RAW you can then have full control over the image in your postprocessing in the computer

In my layman's knowledge, true, which is why white balance is irrelevant in RAW. You can also change the exposure one or two stops either way.

Also note that, at least in Oly, AFAIK the sharpness and contrast settings of "0" actually do some sharpening and contrasting, so I set mine to -2 or so. I have never confirmed this tho...

We need you at our SoCal Oly User Group meetings!! Talk to Sapphire, please! (And I hope to meet you Saturday at the Scuba Show or Casino Night)

I am planning on attending 6/21 (even tho I may not be an Oly shooter by then any more... hopefully). I'll be at the show Saturday afternoon. I am getting on the Encore for an SBI (hopefully) trip Sunday that night, so I plan on staying in the area. I'll PM my cell

Chris

 

[justleesa]

1. Load the image, rotate it, save it, close it.
2. Reload the image, apply color correction, save it, close it.
etc...

Do this a few times and then zoom in on a detailed area. It will start to look bad pretty quicly.

James

hmmm you got me wondering....
When I DL my photos I first create a file with the date that I took the pictures. In that file I have 3 subfiles; original, processed and email.
I get the picture out of the original file, process it and store it in the processed file and then make an email size off that one. After I have a month completed I DL them all to CD and catalog them with my extensis portfolio program.
I never again touch the originals or the processed ones by saving a copy of all really interesting processed photos, as stock photos in a separte file that I leave on the computer.
Let fate have it and say months later I go back to a photo that someone wants from a CD and work on that one...It won't change the quality of the picture on the CD...because data on a CD can't be changed, Right? Or do you mean that down the line that the one and the same picture, after many steps of processing loses quality?

 

[HammerNoMore]

According to all the junk I read from the Mars rovers (which use RAW graphics files), this file type most certainly uses compression algorithms, but unlike JPG's, there's no degradation of quality. That's the whole allure of it over TIF's.

I don't know what NASA's doing but a RAW image should be that, raw data, no compression. TIFF is actually the mother of all file formats. It's tag based and extensable. A TIFF file can be uncompressed, but usually it's LZW (the same compression used in GIF files). After JPEG came out they added tags for JPEG compression.

I know some of the camera manufactures take liberties with what they call "RAW" files but in actuality it shouldn't even have headers. If you want to load it into an imaging applications you should have to tell it the width and hight in pixels for it to be able to render it.

James

 

[herman]

Jasmine, I will let the experts deal with the RAW format but you need to think carefully about what you want the camera for before making your choice. I have a C5050 that I bought mainly for UW use and it does a great job of that but I am somewhat disappointed in it for topside use. I was use to having a 300mm lens on my 35mm and for me, the 108mm on the C5050 does not cut it. It does not bother me too much as it was purchased for use as an UW camera. If I were to do it over I would still get the 5050 but if I had a lot more interest in using it for general purposes I would have to take a serious look at the C740 or 750. I may end up adding a 750 to my camera collection just for the topside use.

 

[archman]

I don't know what NASA's doing but a RAW image should be that, raw data, no compression. TIFF is actually the mother of all file formats. It's tag based and extensable. A TIFF file can be uncompressed, but usually it's LZW (the same compression used in GIF files). After JPEG came out they added tags for JPEG compression.
James

From an online digital photography guide.

The RAW file is a dump of the gray scale data that the CCD captures, and it is then compressed by a mostly lossless compression scheme.This is what gives us a compact file and even more color information than the JPG/TIFF files produced inside the camera.

Here's what's aboard the Mars rovers. They most certainly do not transmit raw data! Nobody knows for sure how that rumor got spread around, but many suggest it was folks confusing "raw" with "RAW" prefixing NASA-released images to the public. Here's what is in fact used.

The ICER image compressor was designed to meet the specialized needs of deep-space applications. ICER is wavelet-based and produces progressive compression, providing lossless and lossy compression, and incorporates an error-containment scheme to limit the effects of data loss on the deep-space channel. ICER achieves state-of-the-art compression effectiveness, providing lossy compression performance competitive with the JPEG 2000 image compression standard, and lossless compression performance competitive with the LOCO image compressor. ICER noticeably outperforms the JPEG image compressor used by the MPF mission and provides significantly more effective ossless compression than the Rice compressor used by that mission.

I only understand a little of this, but the experts on the astronomy forums say ICER works very similar to RAW, especially on the compression aspects.