There are several of areas of differences where image quality is concerned with raw conversion. Let's consider the process, to first order approximation:
- chroma interpolation is the stage where the raw processor takes the bayer matrix data and extracts from it RGB channel organized data ... an intensity map of RGB values layered one on top of the other to produce the final full spectrum color image ... also called "demosaicking". - gamma interpolation is the stage where the linear capture gamma of the sensor is curved to approximate the 2D-PDE gamma response of the human eye. This involves compressing high values together and expanding low values out to one degree or another. - defect removal is where the raw conversion isolates obviously anomalous values (eg: a single photosite's 255 value next to surrounding photosites with 100-110 values indicates that this is a hot or stuck photosite value). - camera calibration profile application is the step where the characteristics of a particular camera are brought to bear in adjusting the final balance of RGB channel mix. Different raw processing algorithms perform each of these operations slightly differently, but the largest influence on the image quality, at least with regards to color and tonal values, is the last step of applying a camera calibration profile. This is the part where Silkypix' close association with Pentax might have some small advantage over other raw processors when used at the raw conversion defaults. Why? Because Pentax shares both their internal camera calibration profiles along with details of how to read the in-camera image processor settings embedded in the raw file as metadata with the engineers writing Silkypix. However, this only really affects the quality of the conversion at the defaults. My testing and evaluation of raw processors is getting a little long in the tooth now, but the end sum of about two months testing with all the capable raw processors in the past showed that all of them could achieve very nearly the exact same thing *given sufficient time and expertise in adjusting their settings*. This last can take substantial amounts of effort in some cases. By and large, the current best practices in raw conversion algorithms are those that Adobe is putting into Camera Raw v6.x and Lightroom v3.x, and there are a couple of competitors (Raw Developer is one) that are almost at the same level. Camera Raw and Lightroom have as advantage a semi-open architecture as you can take advantage of the Adobe DNG Profile Editor and generate camera calibration curves which are arbitrarily close to or better than the ones that Pentax uses, depending on your likes and needs. So, in direct answer to your questions, > Is there a practical way (other than trial and error) to use/copy/replicate > the effect of a curve of, say, Silkypix for another raw developer? Yes. > Or, the curves are hidden, embedded, protected etc.? Yes, well, they're either embedded in the application or supplied to the application in data formats that are not easily decomposed, for software other than the Adobe software. But with the appropriate amount of work, the Adobe software can be manipulated to an indistinguishable value. It's important to remember when thinking about this stuff: digital image processing and chemical image processing are separated by a significant chasm. Chemical image processing has to do with the relative behavior of photo-sensitive chemicals by nature of their molecular structures. This is complex but, from the point of view of a photographer working in a darkroom, provides only a limited degrees of freedom from the baseline established by the nature of the recording medium and the interaction with available chemistry. Digital image processing, on the other hand, is all numbers and mathematics. The degrees of freedom in processing a digital image are substantially greater than the degrees of freedom in processing a film image. It simply requires that you understand how to work the mathematics, through software tools, and have sufficient data to work with. On Thu, Mar 3, 2011 at 1:27 PM, Bulent Celasun <[email protected]> wrote: > (Sorry for cross-posting; no one has replied to this one in the forum > I visit every day). > > I understand that a raw developer software works like the clasical > darkroom "developer" (solution). > There are different varieties producing different outputs from the > same negative/raw file. > In the film days, companies (like Kodak) used to suggest their own > developers for their films. > However, experienced photographers have always used their favorite > film with their favorite developer without necessarily taking those > suggestions into account. > > Now, Pentax suggests Silkypix to develop their raw files. > > Let us say, I like the look of the raw files developed by Silkypix. > And, let us assume that I happen to like Brand X Raw Developer, which > is very good in certain regards. > However, "the look" of the developed file (jpeg or otherwise) is not > that good or just unlike it. > > We know that raw developers apply a curve to the raw data and, like > chemicals used in the film days, these curves result in different > looks. > > My question is this: > Is there a practical way (other than trial and error) to > use/copy/replicate the effect of a curve of, say, Silkypix for another > raw developer? > Or, the curves are hidden, embedded, protected etc.? > > Bulent > --------------------------------------------------------------------- > http://photo.net/photodb/user?user_id=2226822 > http://www.pentaxphotogallery.com/bulentcelasun > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. > -- Godfrey godfreydigiorgi.posterous.com -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
