This class was fantastic. Mike is excellent under pressure when things don't go perfectly, love his style and grace and how encouraging he is to his models, great mentor. I learned so much about using flash, and my pictures are so much better.
The 4MEG VIDEO Model 12 was originally designed tocapture, process, and display image data to a maximum depth of8 bits (256 grey levels). Fortunately, for those interested incapturing greater pixel depths, EPIX engineers have extended thisversatile 8 bit design to capture from 9 to 16 bits!Four Key FeaturesThere are four keys that combine to unlock the Model12's extended pixel depth capabilities. The first key is the additionof enough RS422 receivers to accommodate all of the incoming digitalvideo signals. The second key is the ability to drive the interfacecard and Model 12 with twice the camera's pixel clock frequencyto capture two 8 bit words in the time required for the camerato provide one 16 bit pixel. The third key is the introductionof a 2 to 1 multiplexer to convert a 16 bit pixel into two 8 bitwords. The fourth, and final key, is the ability of the Model12's 8 bit image memory to be configured to accept video datain virtually any array shape or size - in this instance, storinga pixel as two adjacent 8 bit words.(Note: The following discussions assume use of a16 bit digital output camera. The capture method for pixel depthsof 9, 10, 11, 12, 13, 14, and 15 bits is essentially the sameas for 16 bits - a single pixel of 9 to 16 bits is captured astwo 8 bit words and occupies 16 bits [2 bytes] in image memory.)Additional RS-422 ReceiversThe camera outputs a 16 bit pixel as sixteen RS-422differential signals in parallel. Sixteen RS-422 receivers areinstalled on the interface card. The sixteen receivers convertthe RS-422 signals intosingle-ended TTL level signals.Fast Pixel Clock RateThe imaging system uses two pixel clock frequenciesbased on the camera's pixel clock. The camera's pixel clock generatesthe fundamental frequency that drives the camera, and which isalso used by the interface card to generate a second harmonic.The second harmonic drives the interface card and 4MEG VIDEO.This scheme insures accurate sampling by the 2 to 1 multiplexerand provides exact pixel registration in image memory. 16 bitcameras with pixel clock rates as fast as 25 MHz can be interfacedto the Model 12.2 To 1 MultiplexorTTL level signals from the RS-422 receivers are sampledby a 2 to 1 multiplexer. The multiplexer samples the TTL levelsignals as two 8 bit words by using the camera's doubled pixelclock frequency. The two 8 bit words are transferred (sequentially)to the Model 12 and stored in adjacent locations in image memory.The multiplexer is usually configured to sample the most significant8 bits followed by the least significant 8 bits - other configurations,to accommodate various cameras, are possible.Wide Image BuffersFrom a hardware standpoint, the 4MEG VIDEO Model12 operates within standard parameters to capture 16 bit resolution.Flexible buffer definition, an inherent design attribute of the4MEG VIDEO, doesn't care how many bytes are in a pixel, or howmany pixels are in a line - just as long as the total number ofbytes per line is 8,000 or less (if more than 8,000 bytes perline are needed a modification can allow capture of up to 31,000bytes per line).Digital Interfaces EPIX provides interfaces for digital cameras from several manufacturers. Contact EPIX for a Camera Compatibility Guide. When ordering an interface, the customer is instructed to designate the pixel depth required (consult the camera manufacturer with any questions). EPIX technicians will customize the interface card to supply the requested depth. It's important to realize that camera design is a limiting factor, and the customer is cautioned against ordering an interface with a pixel depth greater than the camera manufacturer's specifications. Such an interface will not capture additional data. 9 To 15 Bit Capture vs. 16 Bit CaptureThere are NO 16 bit cameras available today. The16 bit example was used for sake of simplicity. The 8 bit digitalcamera remains the most popular. The 12 bit camera is becomingmore common. Capture from a12 bit camera (or any digital camerathat provides 9 to 15 bits) uses the same principles as capturingfrom a 16 bit camera. Unused data lines are grounded to minimizenoise.Status Of Software Development The 4MEG VIDEO Model 12, with greater pixel depth,is a hardware solution currently with minimal (capture and saveonly) EPIX software support. EPIX technicians have verified thecapture of 16 bits, but then moved to other priorities (such assupport for the EPIX COC40 processor board). Sixteen bit softwarewill be available next year. In the interim, the customer maydevelop custom software or use solutions from third party developers.At least two software packages, compatible with the 4MEG VIDEOModel 12, are capable of 16 bit processing: the Eye Image Calculatorand Image Pro Plus for Windows. Use of Image Pro Plusfor Windows currently requires saving the 16 bit image to diskprior to processing. Once Media Cybernetics finalizes the 16 bitdriver specification, an integral driver will be developed.Status On Display Plans Since the human eye has difficulty distinguishingmore than 64 levels of grey, EPIX has no plans to display morethan the 256 grey levels already provided by the 4MEG VIDEO.Summary The history of EPIX imaging is a history of continuallyevolving hardware and software products that emerge with capabilitiesoriginally unintended. By designing products with a flexible architecture,conducive to modification and enhancement, applications once thoughtimpossible are frequently realized. Sixteen bit capture is oneof these. Many EPIX customers develop custom hardware and softwaresolutions with assistance from EPIX technical support. Complicatedapplications sometimes require shipping custom hardware to EPIXfor testing, software development, and verification. EPIX engineersare always willing to discuss new imaging applications and theneed for new hardware / software features. Many custom developmentprojects are performed at additional cost, but, if the developmentis thought to be of significant interest to other customers, itmight be performed at no charge. Feel free to communicate withEPIX. We are here to help you achieve your imaging goals. EPIX Vision - October 1994 Newsletter EPIX Offers NEW 4M12 COC40 Processing Board EYE IMAGE CALCULATOR Announces New EYEVIEW Software 4MEG VIDEO Model 12 Provides 9 To 16 Bit Capture Back to EPIX Vision Back to the EPIX home pageImage Processing Products For Research and IndustrySpecifications and prices subject to change without notice.
Predator-induced morphological changes that improve the swimming performance of tadpoles are not quite evident (Dayton et al. 2005; Teplitsky et al. 2005; Arendt 2009). We expected that tadpoles that increased their tail fin depth showed faster swimming performance (Van Buskirk and McCollum 2000). However, we found no significant relationship between morphology and performance. GLS models also confirmed these findings; although morphological traits influenced swimming performance differently in each treatment, the models showed no significant effect.
We know that P.thaul tadpoles pre-exposed to predators show enhanced survival (Jara 2010) and that they innately respond to conspecific alarm cues (Pueta et al. 2016) and to caged odonate larvae fed with mosquito larvae (Jara and Perotti 2010). Then, being less active can make these tadpoles less conspicuous when they are at risk of predation, and pre-exposure to caged predators and damaged conspecifics can give tadpoles an advantage when they face a free predator (Alvarez and Nicieza 2006; Mirza et al. 2006; Polo-Cavia and Gómez-Mestre 2014). However, more evidence is needed to find out whether the behavioral plasticity (low activity) of tadpoles exposed to predator risk affects traits (as the morphological changes observed) that are not necessarily related to a functional correlation (tadpole swimming). 2b1af7f3a8