minimal HDR processing

HDR (high dynamic range) editing is our attempt to increase dynamic range of an image taken with any camera which is many stops inferior than our eyes. Cameras, however expensive/ advanced may be the model, are no match for our eyes when it comes to dynamic range. But using software, we may give a modest try to “increase” the dynamic range a bit. As the name suggests, HDR is about having a wider range of exposures in an image, not about making post-apocalyptic images, as we mostly see around.

HDR requires unique modifications for each image. Even if I create a great HDR with one image, I may fumble with the next, because this one may not support the same level of modification. Hence my subject’s exposure at the time of taking the shot will determine how much I must modify it. I should not try to bring all images in same range – that may spoil originality of a scene. To experiment with HDR, we need a scene with different exposure levels in different parts of the frame. In the example below, my frame sees sunset from a roof, so to accommodate the higher-exposed sun, the camera will make the rooftop darker (Image 1). Now if I want a brighter roof, I must over-expose the shot, so the sky becomes whitened (Image 2). HDR will be the fine balance between these extremes (Image 3).

Image 1 – Exposure for sky

Image 2 – Exposure for roof

Place the camera on a tripod and take two exposures of the same frame back to back – in this example one exposure is for the sky and other for the roof. Any decent camera will have “bracket shots” feature, but manually setting the exposure will also do. The two shots now need to be merged into one using a software. No setback due to expensive software; we’ll use good but free products – 1. The GIMP and 2. Picasa. Both are available for Windows/ Linux. In GIMP, open the lighter of the images and on top of that, open the other as a layer. Now  select the darker layer and merge the two layers using “Normal” or “Overlay” mode, sliding the percentage of merge to the scene’s demand. Sliding from the darker layer is better because we want to minimize blown-out (over-exposed) areas as much possible. When you have sufficient details in low and high exposure areas, flatten and save the image.

Image 3 – Increased DR

Now bring all three images to Picasa and study the histograms (you can get histograms in GIMP also, but Picasa provides the simpler one and doubles up as file explorer). You’ll know that you’ve not damaged the frame when the histograms of one of the images and your modified image have similar pattern.

As we can see, the first and last histograms follow similar patterns, hence there is no loss of image data due to this processing. For this reason the processed image doesn’t seem to be out of place.

wordpress vs blogger

Update (11/03/2011): On Google+ storage

Lazy intro (with Disclaimer)

These are perhaps the top two free blogging sites around. Having a Google account, I automatically got one at Blogger. So far I never bothered to use it, as I already have two with WordPress. But today I decided to kill time with it, and I did find some plus points over WordPress. (This is from the perspective of a WordPress user for 6 months, at the same time being a Google user for 5+ years. If you are looking for detailed reviews, there are plenty on the web. Note that I am referring to wordpress.com and not wordpress.org, since we are comparing with the “free” Blogger here.)

Free Space

WordPress offers thrice free space (3 gigs) compared to Blogger (with a catch: Google shares the storage with its other services like Picasa etc.). Assuming half a gig dedicated to Blogger, it should be enough for people with more text to write than fill the blog with space-consuming pictures. A page-long text blog (with links) would hardly take some 100 kilobytes.

Photo-bloggers do appreciate that extra space, but in reality, even 1 gig of space can offer 1000 posts each taking up say 900 KB of a photo and 100 KB of text. One needn’t upload the original big size image file on a website  – it is better to upload a smaller resolution to facilitate quick loading, both for the publisher and reader. Videos can be embedded in the blog, while actually using the storage space from video sharing services like Youtube. One can also embed a photo from another web album, thereby not duplicating storage of the same file.

Update (11/03/2011):
The latest storage specs from Google, considering with/ without Google+ can be found here and here. It seems Google+ is offering unlimited storage for all images uploaded to it which are less than 2048×2048 pixels or 4 MP.

SSO

For Google account holders, Blogger would be attractive with the Single Sign On facility. The same session can be used for mail, chat, blog, web album, docs, etc. Also Blogger is faster than WordPress. But here is one fact: WordPress has a bigger community of bloggers, because this is what it was intended for. Whereas Blogger adds to the number of services Google offers to its account holders. This is why Google shares your blog storage space with its other services. But wordpress is just blogging; no combo offer!

Customization

Perhaps the greatest advantage of Blogger is that it has opened its CSS completely. If you are looking for more control of colors, background and stuff, then Blogger is your stop. In WordPress, one has to purchase CSS upgrade to customize layout, colors etc., if not satisfied with the limited number of themes. In Blogger, one can edit or replace the entire CSS without any paid upgrade. If you are inspired by the better themes of WordPress and know CSS, you can make one for Blogger yourself. And if you want to learn CSS, what better a playground than Blogger? Maybe the addiction will make you open a new blog and publish only CSS templates!

Summary

WordPress is better for space-intensive blogs with 3GB storage, but Blogger has more ability to customize. For bloggers between these extremes, the differences don’t matter; the content of the blog does.