Why don’t digital cameras have better dynamic ranges?

ISO in digital cameras is a digital amplification of the signal. If your camera’s native ISO is 100, setting the ISO to 400 would make the sensor amplify the brightness 4x.

So if ISO is digital, does that mean cameras artificially limit the dynamic range?

Let’s say you shoot a photo at f/8.0, 1/500th sec, and ISO 200. The shadows are clipped. Now you shoot a photo at f/8.0, 1/500th sec, and ISO 400. The highlights are blown out. But ISO 400 just amplifies the signal, and the highlights are well below the absolute maximum limit of the sensor since they look good at ISO 200. Why does the camera cut off the whites early then?

What’s stopping camera manufacturers from mapping a wider range of sensor values to RGB(0-255)?

Managing multiple dynamic database connections

I’m working on a server, which you can pass some form of authentication as input (like connection string) and it will connect you to your database. So the DB connection is going to be dynamic. There can be multiple users at the same time, connecting to different databases.

What I’m wondering is, is there a preferred way of managing the connections? Should the DB Client be stored in memory after authentication, so each user can immediately retrieve it using their session data / and execute queries against it? Or should I close / reopen the connection every time the user wanted to do something. I can use JS to figure out if the user is active on the page / or left and get rid of the connection object using users’ state as well.

Approach 1

  • User signs in to our web application.
  • User enters the credentials to database (like the connection string)
  • Server authenticates against the DB and we now have the connection client object. We keep it in a dictionary mapped to user id.
  • User wants to run a query. We determine the user id from the request, fetch the client from the memory and run the query.
  • When user leaves the page, we detect it through JS (unload event) send a request / or socket packet to server and close the client + remove it from the dictionary.

Approach 2

  • User signs in to our web application.
  • User enters the credentials to database (like the connection string)
  • Server authenticates against the DB and we just confirm that connection worked. We don’t keep the client object in memory.
  • User wants to run a query. We re-connect to the database, run the query and close the connection. No dictionaries are kept in memory, we reconnect every time the user wants to do something.

What do you think?

I have question regarding dynamic sql query

I am trying to execute the below mentioned code block but it is giving me error.

        set serveroutput on; declare   Vquery varchar2(32000); Vitem varchar2(50); Vskuloc varchar2(50); vstartdate date; Vdur Number; vtype Number; vqty float(126); GP_ohpost           Date:= fnc_ohpost; sdate1 date:=to_date('01/01/1970','dd/mm/yyyy'); sdate2 date:=to_date('01/10/2018','dd/mm/yyyy'); c_format  VARCHAR2 ( 100 ) := 'dd/mm/yyyy';  begin Vquery:='SELECT A.Item,A.Loc,A.Startdate,A.Dur,A.Type,A.qty from  (SELECT b.Item      as                                   Item,         b.skuloc       as                                loc,         (to_date('''||GP_ohpost||''') - 7)  as    StartDate,         10080           as                                Dur,         1               as                               Type,     (CASE WHEN(to_date('''||GP_ohpost||''') - h.startdate >= 800 ) THEN                     ((h.PERIOD800) +                       (h.PERIOD799) +                       (h.PERIOD798) +                      (h.PERIOD797) +                       (h.PERIOD796) +                       (h.PERIOD795) +                      (h.PERIOD794))      When  (to_date('''||GP_ohpost||''') - h.startdate < 800) THEN     (PERIOD'||(GP_ohpost - h.startdate)||'     ) Else 0 End) as qty FROM SCPOMGR.histwide h, SCPOMGR.dfutosku b,SCPOMGR.Item c WHERE  h.dmdunit=b.dmdunit AND  h.loc=b.dfuloc AND  c.Item = b.Item AND  h.dmdunit = 431818 AND (b.eff = '''||sdate1||''' OR b.eff <= h.startdate  AND b.disc = '''||sdate1||''' OR b.disc > h.startdate ) ) A        Where NOT EXISTS (SELECT 1 FROM SCPOMGR.SKUHIST d   WHERE a.item = d.item  AND   a.loc =  d.loc  AND   a.startdate = d.startdate)'; Execute immediate Vquery into vitem,vskuloc,vstartdate,vdur,vtype,vqty; dbms_output.put_line('vitem : '||vitem||'vqty :'||vqty);   End; / 

I am getting the below error:

Error report – ORA-06550: line 29, column 28: PLS-00201: identifier ‘H.STARTDATE’ must be declared ORA-06550: line 14, column 1: PL/SQL: Statement ignored 06550. 00000 – “line %s, column %s:\n%s” *Cause: Usually a PL/SQL compilation error. *Action:

Please help me out.

What i am trying to do is i have to concatenate (GP_ohpost – h.startdate) this value(duration) with PERIOD and it will give result like PERIOD63 which is a column and it should give me the value of that column as output.

Does A RAW file exist containing the full dynamic range of a natural scene with a ratio of 100,000:1?

I’ve just read Karl Lang’s excellent whitepaper – Rendering the Print: the Art of Photography. In it, he mentions that the ratio of light to dark in a ‘natural scene’ can have a ratio of 100,000:1, a modern high-end sensor can only capture a range of 8,000 to 1, while a modern pigment printer can only print something like 250:1. He also mentions that it is possible to capture the full dynamic range of a scene using a spectral pixmap though he says this is not practical for general use for reasons of cost and duration of capture. This got me wondering about RAW data generated from sources other than consumer cameras, or created artificially to represent the full possible dynamic range. Do any such RAW files exist? I appreciate that shooting HDR is a way to achieve a similar end, but I’m interested in seeing (and hopefully playing with) a RAW file containing data for the full potential dynamic range.

Fizzbuzz with dynamic height container

Here is a variation on a theme: fizzbuzz. After providing this answer recently, I decided to practice some VueJS skills with outputting the values and conditionally applying styles based on the value. Specifically:

  • red border for Fizz
  • blue border for Buzz
  • purple border for FizzBuzz

And then I decided to allow the user to change the height of the container, in case he/she wanted a smaller viewport.

What, if anything, would you change?

const getIndex = (number, index) => index + 1; const app = new Vue({   el: "#app",   data: {     numbers: new Array(100).fill(1).map(getIndex),     height: 3000   },   filters: {     getOutput: function(number) {       if (number % 3 === 0 && number % 5 === 0) return 'FizzBuzz';       if (number % 3 === 0) return 'Fizz';       if (number % 5 === 0) return 'Buzz';       return number;     }   },   methods: {     getClass: function(number) {       const output = this.$  options.filters.getOutput(number);       if (isNaN(parseInt(output, 10))) {       	return output;       }       return '';     }   } });
body {   padding: 60px;   font-family: serif; } header > h1 {    font: 400 20px cursive; } input[type="range"] {   width: 100%; } #listContainer {   overflow-y: hidden; }  li {   background: #fff;   color: #000000;   border-radius: 4px;   border: 2px solid #6a737c;   padding: 3px; }  li.FizzBuzz {   border-color: #f800ff;  }  li.Fizz {   border-color: #f80000; }  li.Buzz {   border-color: #0000ff; }
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script> <div id="app">   <header>     <h1>     FizzBuzz with dynamic height container     </h1>   </header>   <div>    Height: {{ height }}   </div>   <input type="range" min="200" max="3000" v-model="height" />   <div id="listContainer" v-bind:style="{ height: height + 'px'}">     <ul>       <li v-for="number in numbers" :class="getClass(number)">         {{ number | getOutput }}       </li>     </ul>   </div>   </div>

Understanding Dynamic Frequency Warping (not Dynamic Time Warping)

I am implementing a paper which need Dynamic Frequency Warping as a component. They have written very briefly about this algorithm and cite to this paper: Voice transformation using PSOLA technique (page 9/13 of the PDF, section 3.3). I have read it but can’t understand its mechanic. I’ve also made some search on Google but almost have no improvement. As I understand, DFW take an input of 2 spectra (A and B) and then calculate a warping matrix that convert A->B. Can someone give me some clearer intuition?

Thanks in advance.

Dynamic images

Hello

Is there a way to dynamically change the colors of the product image as the customer selects a different color from product options?

I know this is possible with manually uploading each images and dynamically changing the images as they select different color options but my products have several color options.

You can change the color of:

  1. top
  2. middle
  3. bottom

With each option having multiple color options – that would be hundreds of color combination and…

Dynamic images

Dynamic image

Hello

Is there a way to dynamically change the colors of the product image as the customer selects a different color from product options?

I know this is possible with manually uploading each images and dynamically changing the images as they select different color options but my products have several color options.

You can change the color of:

  1. top
  2. middle
  3. bottom

With each option having multiple color options – that would be hundreds of color combination and…

Dynamic image

Node.js app to keep track of dynamic IP Address of dell edge box?

I have dell edge box that is stored in another location, the edge box is having 4G sim card internet access with dynamic IP address that changes frequently, I usually use ssh putty with the 4G IP address which is IPv6, now if the IP address changes i will not be able to know the updated ip address of the edge box, any ideas how can I keep track of the ip address with a microservice using node.js. Thakns in advance. Seham.