RAW images


icy55

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Mar 13, 2011
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#1
May I know what's the purpose of RAW images. I heard that you can adjust almost anything on it to make it look much better than it originally was. Does that include ISO and everything else?

May I know when do I shoot RAW?
 

SkyStrike

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#2
RAW is not that almighty, It does not do the following

- Recover lost details: Images that are severely over (pure white) or underexposed (pure black) cannot be recovered
- Extend Shutter Speed: if the shot is taken at 1/50s and you get choppy water reflections, you cannot make it like 30 second shutter speed to smoother the water.

*I think probably got more...but this is to my limited understanding*

ISO does not come into the picture here as it's only part of the computation to get a correctly exposed picture. But if you are referring to Removing Noise due to High ISO, yes, there are programs to reduce the noise but at an expense of sharpness.


May I know when do I shoot RAW?
In short, I use Raw if the I want alot of control over my image as in White Balancing, Saturation and Contrasts. Compared to JPEGs which is "dead", as it depends on your camera camera settings of White Balancing, Saturation, Sharpness, Contrasts etc.. when you took that shot.
 

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daredevil123

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lil red dot
#3
You cannot change many things in raw as well. If you Blow the highlights too much, you also cannot recover it in raw
 

ZerocoolAstra

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Mar 13, 2008
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#4
You also cannot turn a lousy composition into a work of art simply because you shot it in RAW :)

In simplified terms, RAW gives you:
a) control over the white balance you apply to the captured image.
b) slightly enhanced ability to capture details from under- or over-exposed areas, compared with JPG. It's not a miracle worker though.
c) an image in an uncompressed, 'unmolested' state for you to work on. Some refer to RAW as the 'digital negative'.

* this list is not exhaustive
 

makolit

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Nov 3, 2010
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#5
the main advantage i find for using RAW is my control over White Balance.
i mainly use AWB when shooting, because i'm lazy. and while the camera does a good job calculating WB, there are times that you may want a certain effect or color cast on the photo to give it more drama. the ability to adjust WB in post processing comes in handy here.

other than that though, the adjustments you can make using a standard JPG file is sufficient, unless you want to be able to adjust with minimal loss to the image before exporting it to JPG. this is usually only important for big prints. if you are just posting things you shot on facebook or online albums, this "loss" in IQ is not really that noticable.

cheers!
 

Octarine

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Pasir Ris
#6
ISO is the technical sensitivity of the sensor in the moment the shot is taken. RAW files are a record of the data captured by the sensor pixels. It is not even a picture in this moment (hence the need for RAW converters). As you can see: ISO is nothing that you can change later. But whatever has been recorded is now available, completely and fully.
JPG is a compression algorithm, designed to minimize the data / file size of images. Upon converting from RAW to JPG the camera removes redundant data from the image according your presets (WB, Picture Style, other parameters). Once gone they are gone forever.
What does it mean? You have the full freedom to process your image in all ways you like. ("Masking look better" is quite subjective.) Example: if you set your camera to record Black / White then the JPG is B/W forever, no way to turn the colours on again. With RAW you can have unlimited amount of possible processing results, the RAW file remains unchanged. In 3 years from now you can still use these old RAW files and create something new...
 

icy55

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Mar 13, 2011
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#7
Wow! Thanks guys! Real good info. How often do you shoot in raw? May I know in terms of post processing how important it is? Can it actually make a photo look much sharper than it really is? Also for image size, raw compared to jpeg how big is the file?
 

Octarine

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#8
Wow! Thanks guys! Real good info. How often do you shoot in raw? May I know in terms of post processing how important it is? Can it actually make a photo look much sharper than it really is? Also for image size, raw compared to jpeg how big is the file?
Erm... bur is blur (whether due to handshake or focus error doesn't matter) and RAW is not a magic wand to correct serious mistakes. RAW is simply the shifting of all in-camera functions back into your hands to have full control. The camera only records the sensor data, nothing else. Everything else is up to you. Whether this is important or not also depends on you. Simple snapshots with properly selected in-camera settings usually do not require extensive post-processing. But as highlighted above by others: in situations where exposure is difficult to get correctly or White Balance then RAW offers all possibilities for correction later. There is no magic formula when to use RAW and when not. Up to you and your skills and requirements.
Regarding image size: it's about 70% of the Megapixel count. My 8 Megapixel cam gives about 5.5MB files in RAW. Size varies slightly between cameras and scenes.
 

ZerocoolAstra

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Mar 13, 2008
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#10
Wow! Thanks guys! Real good info. How often do you shoot in raw? May I know in terms of post processing how important it is? Can it actually make a photo look much sharper than it really is? Also for image size, raw compared to jpeg how big is the file?
As Octarine mentioned, shooting in RAW puts the burden of post processing almost entirely upon your shoulders :)
You have more leeway to correct white balance and minor exposure corrections.

But things like over- or under-exposure, blur due to mis-focus or camera shake. Logically these cannot be rectified even though you shoot in RAW. Garbage in, garbage out...

My 12MP cam outputs RAW files at about 18MB each. So typically a 16GB card can hold about 800+ images.
JPGs are usually much smaller. Even at Large-Fine, I think it's around 1/3 the size (~6MB).
 

snowc

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Jan 8, 2006
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#13
Wow! Thanks guys! Real good info. How often do you shoot in raw? May I know in terms of post processing how important it is? Can it actually make a photo look much sharper than it really is? Also for image size, raw compared to jpeg how big is the file?
Hi TS, I have been shooting in RAW ever since I switched over from JPEG. Personally, I feel that post processing is an essential skill to learn if you want to achieve more with your photos. So I will suggest that you should give it a try too. As for the image size, RAW files are very much bigger than JPEG. RAW files from my camera range around 15 MB. However, it's a factor which doesn't matter to me as memory cards are rather cheap nowadays.
 

JJLoke

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Aug 2, 2009
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#14
RAW saves accurate colours. Good for events where colour reproduction is important.

JPEG algorithm in the camera may give some inaccurate compression, resulting in incorrect colour reproduction

White, light yellow and biege may not be fully accurate in JPEG, same with indigo, violet

An example

My computer CPU LED cooling fan is blue in colour.

When I take in JPEG from the camera, the colour changes to purple. Yes, purple

When I take in RAW, the colour remains blue. Convert to JPEG in computer, remains blue

Conclusion, my camera body JPEG compression gives inaccurate colour
 

daredevil123

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lil red dot
#15
RAW saves accurate colours. Good for events where colour reproduction is important.

JPEG algorithm in the camera may give some inaccurate compression, resulting in incorrect colour reproduction

White, light yellow and biege may not be fully accurate in JPEG, same with indigo, violet

An example

My computer CPU LED cooling fan is blue in colour.

When I take in JPEG from the camera, the colour changes to purple. Yes, purple

When I take in RAW, the colour remains blue. Convert to JPEG in computer, remains blue

Conclusion, my camera body JPEG compression gives inaccurate colour
It is not that JPEG is not accurate. It just means your picture style settings (especially WB) are off.
 

Octarine

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#16
RAW saves accurate colours. Good for events where colour reproduction is important.
JPEG algorithm in the camera may give some inaccurate compression, resulting in incorrect colour reproduction
Oversimplified. The compression itself will not affect anything. Compression removes data which are not required to render the image, based on certain algorithms.
What changes the colours is the automatic White Balance setting (and other settings). Here the camera tries to determine whether there is any colour cast in the image, caused by certain types of lights. The blue light of your fan is recognized as dominant blue cast and the WB is shifted to warm, resulting in Blue becoming Purple. Afterwards the image is compressed and converted to jpg, that's why you have the impression it is caused by the jpg engine.
You can do the same in your own workflow, just shift the WB to warmer setting (lower Kelvin values).
 

WatWatz

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Jan 30, 2011
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#17
What will happen if i use JPEG to edit?
 

SkyStrike

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#18
In short, because JPEG is already a "lost details" format (due to compression), so when you try to edit, you will very likely lose more color details (note: not all the time).
 

JJLoke

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Aug 2, 2009
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#19
It is not that JPEG is not accurate. It just means your picture style settings (especially WB) are off.
Good point, I thought of the problem too, but unfortunately not the case.

Custom white balance with a white A4 paper as reference. Same purple for jpeg.

Shot an indoor event with deep ice blue lighting, casted a light purple tint. Auto/custom white balance cant seem to do the job well

Tried changing WB in PP oso no use.

So in the end just shoot RAW.

Do not have any problems shooting pictures all these years. Now I dun even take notice of the problem :)
 

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ZerocoolAstra

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Mar 13, 2008
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#20
Good point, I thought of the problem too, but unfortunately not the case.

Custom white balance with a white A4 paper as reference. Same purple for jpeg.

Shot an indoor event with deep ice blue lighting, casted a light purple tint. Auto/custom white balance cant seem to do the job well

Tried changing WB in PP oso no use.

So in the end just shoot RAW.

Do not have any problems shooting pictures all these years. Now I dun even take notice of the problem :)
why not the case? I thought Octarine already explained in post #16.
Custom white balance would not work because your reference object is not lit by the blue light from your CPU's LED. The dominant light source is the ambient light in the room (eg. daylight from windows, or indoor tungsten/fluorescent lighting).
Gotta know how custom WB works :)
 

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