HDR Strategies

Very early photographical technique had to face high contrast scenes where the difference between the most luminous areas and the darkest ones clearly exceeded the sensitive surface narrative capabilities of that time.

Besides chemistry, there was the delicate alternative task of photo combination, the addition of two or more images to have a final one that was soon used to alleviate that pressing need of registering detail at both areas of the shot, lights and shadows respectively. Many of the bests pictorialists from about fifties in XIX Century, were breed under this technique.

It is really nothing new, and now is the turn of the digital cameras, to renew the technological speech, a little bit tired at the moment, due to the unfruitful race of megapixels in small captors.

Both cameras in this article offer, from different sources, a combined capture system, whether by the inner division of its captor, Fuji F200, or by the sequential capture of two images, Ricoh CX1. That is: different suggestions for different benefits.

Fuji F200EXR

EXR technology showed for the first time at past Photokina by Fuji is, in our opinion, one of the most suggestive technologies available at the moment. It delivers a true benefit to the shot, being not just another marketing argument, the images obtained fitting the specific needs of the shot, whether a more fine detail description capacity, tonal range or better noise performance.

The fundamentals of this technology have been already studied in many articles in this website, so we think that remembering its characteristics is not necessary. For more information please follow the links below.

The captor of this Fuji F200EXR is able to reassign its photodiodes, giving a maximum resolution of twelve Mpx, HR mode, or combining the information of those diodes with an improved «pixel binning» resulting then in six effective Mpx.

This strategy is divided also in two different modes, priorizing upon dynamic range, assigning two photodiodes for each final pixel, one for highlights and the other one for lowlights or priorizing for low electronic noise, combining then their photodiode surfaces, to obtain a better high ISO noise response. These are DR and SN modes respectively.

In this article, when we take the comparative shots with the Ricoh CX1, we will focus on this last modes, specially the DR one, the dynamic range priority.

 

DR Mode, High contrast exterior

SR Mode – Inside ISO 800

 

Both images show up the benefits obtained by an effective photodiode combination in the very same captor, thanks to EXR, a camaleonichal Technology built-in the camera that changes its resources in order to fit a given shot.

 

Ricoh CX1

Ricoh, represent always a source of good news, building a constant and coherent photo criteria, and the CX1 represents an evolving twist opposite the R10, not only downgrading the resolution from 10 to 9 Mpx, but also getting up into technological renovation, that will be very important in the very next few years.

Among other characteristics offered, apart from a very suggestive HDR in-camera mode, it is very well built and has a superb finishing quality, and this is where Ricoh always makes the difference.

This HDR mode, called DR in Ricoh, captures two images with different exposures, and then joins them in a final one, with a higher dynamic range.

So, as we said above, this skill is as old as photography itself, and its actual praxis is very complex, being fully recommended a good tripod, mirror lock-up and bracketed shots, and digital post-processing, whether layer masks in Photoshop or the dedicated programs or plug-ins.

The CX1 tries to avoid all of this, achieving a fast and automatic fusion of both captures. Good fusion even in hand-held long exposure shots, impossible to achieve in the DSLR world, but it is also an important issue not to overestimate the CX1 capabilities: in action scenes it can make double-image shots, so let’s don’t ask CX1 what it can’t give to us due to its market target.

It has, also, an improved interpolation algorithm, optimized to get, according to the Firm, a correct exposure in the higher tones one step further, minimizing the jpg loss of data in the highlights. In addition to the DR mode, all of that gives an effective synergy in the complexity of exposure. This DR mode has four functionality levels: high, medium, low and very low, according to the complexity of the scene itself. This function is easy to handle, according to the CX1 kind of camera. We’re looking forward, in next models for a higher level of control in this function. Who knows if a future “GX300” , can fit in its profile more control options in this DR mode, bracketing, or separate EV compensation dials for each image, for instance.

 

Normal capture

 

DR High mode capture

 

CX1 is the first compact Ricoh camera incorporating a CMOS sensor, maybe chosen due to its very low power consumption and fastness, rather than a supposed better signal/noise ratio in high ISO, yet the size of the photodiode is still demanding in this matter, and the pixel pitch in this CX1 is correct but could noticeably be improved.

We have to downgrade the number of effective pixels in the sensor in order to have them with a higher useful surface, because then a lesser degree of electronic amplification of the signal is needed and so there is less electronic noise. Seven or eight millions pixels is a good choice for all the applications, even the most demanding ones, in our humbly opinion.

For this CMOS having a positive impact in the speed of the camera, an acceleration in the shutter operation process is needed, and also the in-camera image processing, the first thing achieved with sensor shuttering instead of an electronic-controlled mechanical one, and second thing, with a high speed image processor able to combine the two images obtained in DR mode at the very same moment.

 

Comparative

Technical comparisons are always hard to quantify, due that most of the variables of the comparing process are important bits only seen under an expert and patient eye, extracting benefits of one against the other one, always under his own opinion, where one person may see a good advantage and vice versa.

To avoid this subjective opinions the working method must be the most scientific and objective possible, and as for the matter of this article, for the HDR images taken with both cameras, the bright difference offered must be exactly measured, in photographic slang, extracting its contrast relationship to take in consideration the effectiveness of the different HDR strategies proposed.

And, to read an measure the light, we take now from our dusty shelves a reliable and well-tested spot meter whose high precision will enable us to get our first comparisson shots.

High contrast subject

The graphic above represents the EV, from various selected parts of the image, let’s remember that EV doesn’t represent a concrete relationship between diaphragm/shutter but a reciprocal one, giving us a brightness level that could be captured by several diaphragm/shutter proportional relationships. The EV values in this graphic were taken with 100 ISO.

With a 9-stop brightness difference, from 7 to 16 EV, between darkest and brightest areas respectively, the scene is perfectly disposed to extract the maximum narrative capacity in low and high lights, from the technologies here in discussion.

To fit the size and scale of both images, the higher resolution shots from the CX1 have been downsampled to six million pixels, in this process we have very carefully considered the interpolation mode, in this case the approximation one, so as not to influence the noise level of the image. If we had downsampled in the bicubic sharpened mode, the noise patterns would be changed although they should be processed in the interpolation process itself.

Both HDR models were set in their maximum effectiveness level, DR 800% in the Fuji F200, DR High in CX1, with same exposure settings. At this point of the test, we are shocked by the big visual difference between both shots. This could be due to several causes, either a false ISO index, automatic compensation exposure adjustments, and so forth, but we think that this is because the HDR character process of this cameras. As they are very different in HDR, their peculiarities shouldn’t be less different.

 

The F200 makes HDR from two different types of photodiodes, and then combining the respective signal based in the exposure settings. On the other hand, CX1 uses the exposure settings as guidance to the second shot, usually setting a longer shuttering or a lower ISO index to have its remarkable HDR highlight recovery data.

Under a close inspection, we can see how different are the cameras: on one hand the CX1 files have more highlight detail recovery, really awesome in fact, though we think it should be very important to work harder in the technology of combining those inner shots because it’s not difficult to see some «reciprocal intoxication» in the final image, having underexposed areas in the shadows and an important posterized in the brightest areas. The processing image is also too hard, loosing a great amount of detail in the final image.

On the other hand, in DR mode the Fuji F200, preserves a better detail in the whole image area, even with nominal resolution being lower, and that thanks to an effective «pixel binning» as it exposes correctly the darkest areas, with less noise, but it can’t achieve as good highlight detail as its rival here. Remarkable its coherent relationship between its final photodiode size, and its resolution, six megapixels of «high quality», having less noise than CX1.

We can look into this feature deeper in the next technical test image, a low-key shot extremely complex in the very highlights for noise and exposure control.

A high contrast low key

 

We rise up to a little bit more than ten stops the contrast ratio between extreme black and white, and we put in there lots of hurdles. Directly or indirectly self illuminated objects, specular shines, fine detail textures and tiny objects, and even a black cloth with delicate lightning. Nice low key to show us up electronic noise.

Fuji F200 DR 800% / Ricoh High DR

The balance of the dispute between both cameras remains again even, shadows areas showing better exposures, sharper and with less noise in all the cases with the Fuji F200, and as for highlights, including specular lights, they are better handled by Ricoh CX1. The problematic white balance situation, with mixed dominants, is resolved in a more neutral way by the Ricoh, thanks to a new multipattern WB system, giving different corrections for different dominants in the scene, with a selective zone performance.

Both of them, anyway, downgrading the HDR ability to average levels, Fuji F200 DR 400% and Ricoh Medium DR, exposes better in shadows and lights, being more noticeable this improvement in the CX1, where High DR gave us a very important shadows underexposure.

DR intermediate adjustement, both cameras

Conclusions

The hardest challenge those cameras have to deal with, is beneath many variables, all of them important ones, and any choice and change in any of them, will change all the product itself. The size of the captor, its nominal resolution, the optical quality, equivalent focals, size and weight, and last but not least, a maximum recommended retail price closing the circle.

The success in this purpose is to be right with the target very carefully, avoiding overlaps among models of the same brand, and those cameras fit perfectly the demands and expectations of the average customer.

We’ll have to wait the evolutions that these suggestive HDR proposals have in their consecutive models, especially among the advanced compact cameras, where more extensive manual settings will be very appreciated. (*)

Praiseworthy is the effort of both brands overtaking a delicate economical situation, when innovation in this saturated technological market is needed.

The choice is so subjective and always open to doubt, if we focus on the captor performance about noise and detail, the Fuji F200EXR really makes the difference. However, if we prefer dailight, well-lighted scenes, the wider dynamic range of Ricoh CX1 is undeniable, and then very convenient.

In an ideal world where brands put in contest their tools and technologies giving birth to an almost-perfect model, it seems like a chimera to the users who are tired because of the willful obsolescence that ruins their wounded finances, before that wishful thinking comes the commercial reallity…. of the real world.

(*) A month after publication of this article, models FinePix S200EXR and F70EXR have been launched with same captor EXR technology

 

Fujifilm Finepix F200EXR camera(Spanish)
Ricoh CX1 camera (Spanish)

Manuel San Frutos
Licenciado en Bellas Artes con estudios parciales en Historia del Arte y Antropología. Funambulista entre la estética y la práctica fotográfica, que imparte y publica regularmente desde 2005 para diferentes audiencias y medios. En estos momentos, centrado en la coordinación de un equipo del cual no podría estar más orgulloso.
       

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