Hello. Latecomer to the HDR Scene w/ my New Canon G11

[AWorkOfMarc]

Hello peoples!

I'm so novice I am probably far off most of your radars.

In some magazines and online, I've been seeing HDR images for some time now but never knowing what they were (other than cool photos) or that there was an actual technique to it.

Then I came across something online about them. So I ran out and bought the best camera (I know the camera is a truly a po-dunk beginner's camera but we all gotta start somewhere) I could afford for right now (Canon G11) and I am going to try my hand at learning how to take / make good HDR. I saw the tutorial on here -- if anyone knows of any others, or an exceptional book on the subject.. please holla at me.

Thanks!
Marc

[Colin Southern]

Hi Marc,

Welcome to CiC - it's great to have you with us

HDR is really just a technique (or set of techniques) for capturing a range of brightness of a scene that's too big for a camera to handle in one shot all by itself, so we usually give it a helping hand using tricks like graduated filters, or taking multiple exposures and then combining them in post-processing. What we're seeing a lot of also though, is images with surreal skies and other artistic interpretations ... although these are often (and incorrectly) called "HDR" images, in reality, they're a processing choice that's often performed at the same time as the HDR rendering, but in reality good HDR can also be photorealistic. Eg this image posted by our (somewhat quiet) expert GUI ...



PS: Sorry, but I've trimmed your eMail address from the bottom of your post ... you seem like a nice guy, and no nice guy deserves that much spam!

[AWorkOfMarc]

Yeah, I've been reading about the "how" of HDR using bracketed photos (and, sorry, I just realized I started this thread in the wrong forum, should be in HDR)

Tis was my first attempt taken earlier tonight using 3 raw formated images (reg. under and over) and photoshop cs5 merge tool. Shown is only the reg and the hdr'd one. Not much difference. Guess I have some reading and experimenting to do.

[Colin Southern]

Hi Marc,

I've moved the thread to the HDR forum for you - no charge

When shooting HDR you really have to bracket the exposures to capture the range of brightnesses that you want to preserve - in the case of the image above you've got blown detail on the right from the lights, and very dark shadow areas at the bottom which most wouldn't want in an HDR photo, but at the same time, it's also going a long way towards making it look photorealistic, which (in my opinion) is a good thing.

Keep in mind too that even when you've been through the HDR process you STILL need to process the image like you would any other image (ie adjusting levels etc). Often people get hell bent on "needing HDR", but in reality, if they shoot RAW, there's often more than enough detail hidden in the shadows than only needs to be revealed by using the likes of Adobe Camera RAW's fill light control.

[Inkanyezi]

Although most HDR software suggests a series of several bracketed pictures (often three, spaced by two steps), for most HDR pictures you need only two, if you know your equipment and its dynamic range right. A Canon G11 for example makes use of the full 12 steps available in its A/D converter, although 10 steps is more reasonable for reasons of shadow noise. Noise may be a reason for using more exposures, but taking only two saves time in processing. Thus, two exposures, spaced by four steps, would mostly give you the same result as the series of three, but in less time, as the software will work quicker and use less memory with fewer shots.

What has to be taken into account is primarily the highest luminosity that you want to render in the final photo. For a Canon G11, this is a simple matter. You load CHDK in the camera using a prepared memory card, and set it to Zebra Mode, to show blown highlights real-time. Adjust until only the highlights that you accept blown-out are zebraed, and this is your highlight shot. Then another shot at four stops more will take care of the rest. In practice, you will get 12 stops of dynamic range from the jpegs, and you may get up to two more stops from the RAW files, depending on what ISO setting you used. Full dynamic range is only acquired at lowest ISO, and it drops almost linearly when you raise ISO. Theoretically, there will be 14 stops available, although the lowest levels then will have much noise and few digital levels. To simplify the process, you may let the camera shoot three exposures and only use two of them, but it is important that the highlight shot is done so that only specular highlights and light sources reach saturation.

Of course a script for CHDK may be made to automate the process.

[AWorkOfMarc]

NEVERMIND -- I found it!! -- thanks!

it's: g11-100l-0.9.9-928-full_BETA.zip

Hi.. So I basically get what you are saying. However letting it absorb, I run to find this CHDK you mention.. read about THAT -- but then come to find out Canon G11 is not supported. (per: http://chdk.wikia.com/wiki/Official_...rmware_updates ) -- Only up to the G10. Which I thought about loading but then decided not until I am sure it won't mess things up. Anyways -- that you very much for your detailed answer.

Marc

You load CHDK in the camera using a prepared memory card, and set it to Zebra Mode, to show blown highlights real-time. Of course a script for CHDK may be made to automate the process.

[AWorkOfMarc]

May I please intrude just briefly once again to ask about loading CHDK? The directions are not real clear... and when I thought I did it right -- I did not get the "Firm Update" menu the directions said I would.

I loaded the vers.req and the DISCKBOOT.BIN in the root area of the memory card - and the FOLDER entitled CHDK (with all its sub folders inside) in the same root area of the memory card. However I'm wondering now since, like I mentioned, it will not load the "Firm Update" if I should remover the syscurves.CVF file and all the sub folders (DATA, GAMES, SCRIPTS, CURVES etc.) from the CHDK folder and put them in the root directoy too?

I'm afraid to screw things up now.

UPDATE: I may have found out the problem. These directions at: http://chdk.wikia.com/wiki/CHDK_for_...DK_in_the_card -- say I should be using a 4 GB card. Mine is 8 GB. Would the be the reason?

[Inkanyezi]

There are a couple of compilations for the G11 on the CHDK site, and it is important that you get the right one for your firmware. The CHDK program is not really a firmware, but a program to let you use the features that are in the camera firmware.

It might not work on a SDHC card in a G11, as a SDHC might not boot. You might need a 2GB SD card to boot the camera with CHDK. The manual method of loading by "firmware update" is not supported by the G11. So you might need a raindance to make the card bootable, which I don't know how to do in Windows, but there might be directions on the CHDK page (I use Linux).

SDHC cards won't boot my camera, a G7, but it boots perfectly with SD cards (max 2GB).

[AWorkOfMarc]

I'm going to order a 4 GB since it was stated in the directions "no more than a 4GB".. but I'm also going to start a NEW thread asking if anyone else has loaded that onto a G11 and see what their experience was. Thanks for you time Mr.

There are a couple of compilations for the G11 on the CHDK site, and it is important that you get the right one for your firmware. The CHDK program is not really a firmware, but a program to let you use the features that are in the camera firmware.

It might not work on a SDHC card in a G11, as a SDHC might not boot. You might need a 2GB SD card to boot the camera with CHDK. The manual method of loading by "firmware update" is not supported by the G11. So you might need a raindance to make the card bootable, which I don't know how to do in Windows, but there might be directions on the CHDK page (I use Linux).

SDHC cards won't boot my camera, a G7, but it boots perfectly with SD cards (max 2GB).

[Colin Southern]

It's been a few too many years since I've worked on low-level disk access, but somewhere in the back of my mind I had a feeling that a different file system may be needed to address media over 4GB - so it's possible that the camera's bootstrap loader can only work with the file system of a 4GB device.

Just a theory -- could be wrong, and I often am!

[Inkanyezi]

You're right Colin. With a large card, you might need a smaller boot partition for the camera to boot. I have tried it on mine, to no avail, but as the G7 does support loading via "firmware update", it's not a problem for me. However, as the G11 does not support the "firmware update" method, the card must be prepared for booting. It's trickier to do with SDHC, and it might not work with all cards. With an SD card (2GB), it's just to make it bootable.

I don't know whether the G11 has a highlight warning in playback, but that's one workaround that has to be done with most DSLR cameras to check that you're not blocking up highlights. A not so exact method is just to use compensation -2, which will probably save the highlights, although for scenes that have no really bright spots, it is more than what's needed, and you will miss many digital levels in the highlights as well as in the shadows. With digital one should try to be as close to saturation as possible.

Of course by far the simplest way of getting the shots is to set the bracketing to +2, 0 -2 and use only the +2 and the -2 images. If a script is done to shoot only these two, there is less risk of movement of parts of the scene, but the bracketing method built into the menu system is simpler to use than making a scriptt and loading the software in the camera. The point however is that taking more than two exposures generally is an exaggeration, and as the dynamic range even of a jpeg is about 8 stops, a difference of four stops still provides a 4 stop overlap of the exposures. The "middle" 0 exposure is redundant and is only hogging the computer when it processes the image.

CHDK is a tool that is easy to use for highlight control, as it has the "zebra mode" that blinks real time for blocked hightlights when you frame your subject, and there is also a red arrow at the right upper corner of the histogram that indicates when there are blocked highlights. These features are visible on the screen before the picture is taken.

The directions on the CHDK page may work or not with your camara and cards. I read the instructions back and forth, formatted a small bootable FAT16 partition onto my 4GiB card in order to make it boot, but to no avail. The camera simply does not boot unless the card is SD, not SDHC. So if you want to use it for the nice features it has, I'd suggest using SD and not SDHC.

[AWorkOfMarc]

Wow. Again thank you SOOO much for your detail in answering. I'm first going to get an SD 4gig if that does not work then a 2gig! =)

[Inkanyezi]

I have now again tried a 4 GB card and formatted it in the computer to FAT16, before making it bootable in the camera, and alas, it works.

So for a G11, I guess that the card tricks mentioned on the CHDK page would be needed to get the card bootable. I.e. there must be a FAT16 bootable partition as the first partition on the card, but it does not suffice to mark it bootable in the partition editor. A hex editor is needed (or the "card tricks" software) if the card cannot be made bootable in the camera, and when the string BOOTABLE is written at the 0x40 position on the boot partition, the card should boot when it is write protected.

There are instructions on how to do it on the CHDK site, and they must be followed meticulously. I did it the easy way, as I don't have any larger cards than 4GB, but for an 8GB card you must make a small boot partition that is FAT16, which should be the first partition on the card, and format the rest of the card FAT32. That's what I tried earlier to no avail with my 4GB cards, but I have realized that I didn't do it right. The partition must be marked as indicated in the Wiki, with the string BOOTABLE in the right position of the boot sector. I assume that the "card tricks" software does this, but I don't use Windows.

So, revisiting the CHDK Wiki helped me too, because now I can have my camera boot also with large cards.

Good luck!

[AWorkOfMarc]

Oy oy oy... but I dunno how to make a FAT partition. I just ordered a SD 4GB card though. So maybe I'll just try that first before I go sticking even MORE pins in myself <grin> Still it'd be a good thing to learn I suppose...

[Inkanyezi]

As Dave Humphries points out, I made an error. The first partition must be FAT16 (I corrected that in the post now).

But a 4GB card can be entirely FAT16, and that's why it works with 4GB. But normally, if you format a 4GB card disregarding the FAT setting, you will get a FAT32 partition that cannot boot the camera. The tools mentioned on the CHDK site should work, and also the partition manager in Windows can make a FAT16 partition.

Of course, you can sidestep the whole procedure by just using the built-in bracketing and to save time and number-crunching, use only the dark and bright exposures.

[AWorkOfMarc]

WHOA!! Success!! Thank you guys soooooooo muchfor walking me through this. i went over to a IT friend's house last night and using Card Tricks he helped teach me how to go through the process of partitioning a SD memory card (all we had was a 128 mb one to work with, until my 4gb arrives) we got the CHDK on the card and the menus show up fine. NOOOOW I can start learning abot all the new options available, in specific that Zebra one that was mentioned and what was got this whole thing started. Again --I can't even begin to thank you enough. What an awesome forum =)

Marc

[Inkanyezi]

There are drawbacks. Either instead of reformatting when emptying the card, something that should be done regularly, you will have to erase the pictures to start over, or you'll have to go through the cardtricks process again. This will of course be learned and become standard procedure.

There are other nifty things also in the CHDK program. For example the histogram, that is transparent, where you have indicators of highlight and shadow. Instead of zebraing, you might rely on the live histogram, that shows burned highlights with a red arrow outside the upper right corner. However, the zebra is my preferred method, because often I would allow some hightlight, i.e. light source orr specular highlight, to burn out, but this will of course be indicated by the red arrow. When deciding to take a HDR picture, the zebra mode shadow feature will show whether the scene fits into one normal exposure or if you have to use more than one.