2009年1月21日 星期三
Viewing Large Images - OpenLayers, GSIV, ModestMaps, DeepZoom, and Python
Viewing Large Images - OpenLayers, GSIV, ModestMaps, DeepZoom, and Python
November 30, 2008 by kapilt
Lately
I’ve been experimenting with displaying very large images on the
internet via a web browser, with pan and zoom functionality. The guts
of this functionality are the same regardless of implementation. On the
server, a tile cutter processes a large image, and constructs an image
pyramid. The image pyramid is a hierarchical structure composed of n
levels of the same image at different resolutions. Starting with the
bottom level as the original image, each successive level reduces the
image size by half, and the process is repeated log_2( max( width,
height)) times until finally an image of only 1 pixel (average of
entire image) is generated as the top of the pyramid. Each level’s
image is split into a set of fixed size tiles. A web browser client
implementation ( flash, ajax, etc) constructs a zoom interface, that
responds to zoom in events by moving the viewport progressively further
down the pyramid, showing tile images of the larger resolution to give
the effect of zooming into an image. A nice illustrated write up of the
concept can be found here. I’ve probably made it sound more complicated than it really is.
The initial implementation I was working with utilized OpenLayers, which implements a client for accessing OpenGIS Web Feature Servers (WFS) and Web Mapping Servers (WMS).
Unfortunately the size of the library seems to be constantly increasing
(~200K in the last year) and currently weighs in at 560K uncompressed,
and requires a special implementation to serve up the tile images, ie.
a WMS Compliant system, in this case TileCache. For scaling and efficiency purposes, I’d much prefer to directly serve these images off a CDN, disk (nginx), or via varnish
and bypass any application code. Additionally the sheer size of the
OpenLayers code was unwieldy for the integrations requirements I had,
which did not include any GIS functionality.
Surveying the land for other non-commercial image viewers, turned up a few of interest. GSIV
( Giant Scalable Image Viewer), was a fairly basic but capable
javascript based viewer, that fit my requirements bill, small size at
26Kb uncompressed, and focused on pan and zoom functionality (demo).
However as a project it appears to be abandoned, and hasn’t been
touched in two years, although several patches have been submitted
which retrofit the implementation using jquery are extant.
I came across ModestMaps next, which is a flash (2 & 3 ) based implementation, with a small size (demo).
One nice feature of modest maps, is that it performs interpolation
between successive levels giving a smooth zoom experience to an end
user unlike somewhat jerky experience that GSIV produced. Unfortunately
being flash based meant a whole different chain of development tools. I
looked around at what was available for an opensource flash compiler
toolchain and found MTASC (Motion Twin Action Script Compiler ) and Haxe.
In the end i decided against it, partly due to its GIS focus, and the
customization/ maintenance cost for developing on propretiary platform
(Flash). Despite that, i think its the best of the opensource viewer
implementations if your already have/use an adobe flash development
stack.
I was set on using GSIV, and then i came across a blurb on ajaxian
about Seadragon Ajax and Deep Zoom from Microsoft’s Live Labs.
Microsoft’s done some impressive work with image manipulation over the
last few years. The PhotoSynth TED talk is one of the most impressive technology demos i’ve seen to date. Deep Zoom is a SilverLight technology ( more propretiary platform lockin), that allows for multiscale image zooming with smooth zooming. The Seadragon Ajax
is a javascript implementation of the same functionality in a 154k
library ( 20k minimized and gzipped). It fit the bill perfectly,
standards (javascript) based, image zoom and pan, with a great user
experience. One problem unlike all the other tools mentioned here,
which have python based tile cutting implementations, Deep Zoom was
utilizing a Windows only based program to process images and cut tiles.
I had a couple of hundred gigabytes of images to cut, and not a windows
system in sight. But based on this excellent blog write up by Daniel Gasiencia,
I constructed a python program using PIL that can be used as a command
line tool or library for constructing Deep Zoom Compatible image
pyramids. It can be found here,
hopefully its useful to others. As a bonus, it runs in a fraction of
the memory (1/6 by my measurements) needed by the GSIV image tile
cutter and faster as well ( 100 images in 5m vs 1.25hr). Unfortunately
the Seadragon Ajax Library is not opensource, but non commercial usage
seems to be okay with the license, and i’ll give it over to some
lawyers to figure it out.
To process the several hundred gigabytes of images, i utilized this library and wrote a batch driver utilizing pyprocessing remote queues, a small zc.buildout and cloudcontrol to process the images across a cluster, but thats left as an implementation detail for the reader
2009年1月20日 星期二
Image Optimization 讀書心得
前言
上個月在 YUI Blog 上有 4 篇 Image Optimization 的連載，若你重視網站的效能，這篇是非常經典且必讀的文章。
主要在於圖片格式的介紹、使用免費的命令列工具縮小圖片但不失真。難能可貴的是，作者 Stoyan Stefanov 也做了許多的實際測試，讓這系列的文章非常有說服力。以下為文章列表：
http://josephj.com/entry.php?id=209
Flash Image Zoom
http://www.flashden.net/item/zoom-pan-controls-with-dynamic-image-settings/15713?page=5
2009年1月15日 星期四
2009年1月7日 星期三
PHP: Object Oriented Web Forms
As I've gone from project to project over the years I've built up my
personal code library. One piece of code that I've found extremely
useful time and time again is an object oriented class for building web
forms. It allows me to keep consistent looking/acting forms throughout
a web application, rapidly develop new forms, make global changes by
editing a single file, and keep all the logic of a form within one file.
The following code and examples are for php version 5 or higher.
Example 1: The Basics
include("forms.php");
function Button1Clicked(&$data,&$error){
$error .= "Field 1 = ".$data["field1"]."<br/>";
$error .= "Field 2 = ".$data["field2"]."<br/><br/>";
$error .= "You clicked Button 1. <br/>";
return true;
}
$form = new form("myform");
$element = new form_element_text("field1","Field 1","This is field 1");
$form->add($element);
$form->newline();
$element = new form_element_text("field2","Field 2","This is field 2");
$form->add($element);
$form->newline();
$element = new form_button("Button 1","Button1Clicked");
$form->add($element);
$form->run();
Example 2: Pre-loading Data
function LoadData(&$data,&$error){
// Load initial data here.
$error .= "Data Loaded!!<br/>";
return true; // return true to show form and false to not show it.
}
...
$form = new form("myform", "LoadData"); // Call LoadData on load.
...
Example 3: Buttons
...
function Button1Clicked(&$data,&$error){
$error .= "You clicked Button 1. <br/>";
return true;
}
function Button2Clicked(&$data,&$error){
echo "You clicked Button 2. <br/>";
echo "<a href='example3.php'>Click here to go back.</a>";
return false;
}
...
$element = new form_button("Button 1","Button1Clicked");
$form->add($element);
$element = new form_button("Button 2","Button2Clicked");
$form->add($element);
$element = new form_button("Button 3");
$element->submit = false;
$element->on["Click"] = "alert('You clicked Button 3!!');";
$form->add($element);
...
Example 4: Individual Element Styling
Most of the styling is done via the forms.css file but occasionally you'll need to apply a style to an individual element.
...
$element = new form_element_text("field1","Field 1");
$element->style = "width: 400px;";
$form->add($element);
...
Example 5: Validation
Form validation is done through making an element required and/or
applying a regular expression to an element that the value must match.
If you need more complicated validation then you would put that logic
within the function associated with a form_button.
...
function Button1Clicked(&$data,&$error){
if ($data["field1"] == strtoupper($data["field1"])){
echo "Form Validated!<br/>";
echo "<a href='example5.php'>Click here to continue.</a>";
return false; // Don't show form.
}else{
$error .= "Field 1 must be all uppercase.<br/>";
return true;
}
}
...
$element = new form_element_text("field1","Field 1","UPPERCASE only.");
$element->required();
$form->add($element);
...
$element = new form_element_text("field2","Field 2","Integer value only.");
$element->required();
$element->regex("\d+","Field 2 must be an integer.");
$form->add($element);
...
Note that Button1Clicked() never gets called until the built-in form validation passes.
Example 6: Other Form Elements
...
$element = new form_element_text("field1","text");
$form->add($element);
$form->newline();
$element = new form_element_password("field2","password");
$form->add($element);
$form->newline();
$element = new form_element_textarea("field3","textarea");
$element->cols = 50;
$element->rows = 3;
$form->add($element);
$form->newline();
$element = new form_element_checkbox("field4","checkbox");
$form->add($element);
$form->newline();
$element = new form_element_select("field5","select");
$element->option("","");
$element->option("option1","Option 1");
$element->option("option2","Option 2");
$form->add($element);
$form->newline();
$element = new form_element_select("field6","select (multiple)");
$element->multiple = true;
$element->option("option1","Option 1");
$element->option("option2","Option 2");
$element->option("option3","Option 3");
$element->option("option4","Option 4");
$form->add($element);
$form->newline();
$element = new form_element_radio("field7","radio");
$element->option("option1","Option 1");
$element->option("option2","Option 2");
$form->add($element);
...
Download the Code
forms.php
The form class to include in your php code.
PHP: Easy Tabs for your webpages
PHP: Easy Tabs for your webpages
Mon, 04/21/2008 - 14:44 — jondale
Easy tabs is a short and simple php class that makes it very easy to have tabbed dialogs in your webpages.
Usage
$tabs = new tabs("mytabs");
$tabs->start("Tab1");
// Tab1's content goes here....
$tabs->end();
$tabs->start("Tab2");
// Tab2's content goes here...
$tabs->end();
$tabs->run();Examples
Here we just create 3 tabs and put some text in each one.
include("tabs.php");
$tabs = new tabs("example1");
$tabs->start("Tab #1");
echo "This is tab number one.<br/>";
$tabs->end();
$tabs->start("Tab #2");
echo "This is tab number two.<br/>";
$tabs->end();
$tabs->start("Tab #3");
echo "This is tab number three.<br/>";
$tabs->end();
$tabs->run();View Example or Download Source
For a bit of a more complicated example, we use the forms class from a previous article to put some simple forms in each tab.
include("tabs.php");
include("forms.php");
function Form1_Button1_Clicked(&$data,&$error){
$error .= "You clicked button 1 on Form 1!<br/>";
return true;
}
function Form2_Button1_Clicked(&$data,&$error){
$error .= "You clicked button 1 on Form 2!<br/>";
return true;
}
$tabs = new tabs("example2");
$tabs->start("Form 1");
$form = new form("form1");
$element = new form_element_text("field1","Field 1","This is field 1");
$form->add($element);
$element = new form_element_text("field2","Field 2","This is field 2");
$form->add($element);
$element = new form_button("Button 1","Form1_Button1_Clicked");
$form->add($element);
$form->run();
if ($form->submitted){ $tabs->active = "Form 1"; }
$tabs->end();
$tabs->start("Form 2");
$form = new form("form2");
$element = new form_element_text("field1","Field 1","This is field 1");
$form->add($element);
$element = new form_element_text("field2","Field 2","This is field 2");
$form->add($element);
$element = new form_element_text("field3","Field 3","This is field 3");
$form->add($element);
$element = new form_button("Button 1","Form2_Button1_Clicked");
$form->add($element);
$form->run();
if ($form->submitted){ $tabs->active = "Form 2"; }
$tabs->end();
$tabs->run();View Example or Download Source
Download
If you would like to use Easy Tabs you can download and include the tabs.php file below.
Also included is a sample tabs.css file to get you started on styling it to fit your website.
memcached - 解決高流量問題
memcached - 解決高流量問題
# 文章來源 http://www.ecstart.com
# 作者 : FIEND
# 轉貼請註明出處
###################################################
介紹 :
現在機器的記憶體真的比起過去便宜太多了....
看到這個套件 感觸蠻多的 ^^ ....
使用這個套件 必需是個有經驗 而且具備分析和規畫能力的 programer ..
因為它必需要建置 services 時 就開始想怎麼去規畫它 .
http://tw2.php.net/manual/en/intro.memcache.php
什麼是 memcache :
memcache 官方網站的介紹 -
memcached is a high-performance, distributed memory object caching
system, generic in nature, but intended for use in speeding up dynamic
web applications by alleviating database load.
Danga Interactive developed memcached to enhance the speed of LiveJournal.com, a site which was already doing 20 million+ dynamic page views per day for 1 million users with a bunch of webservers and a bunch of database servers.
memcached dropped the database load to almost nothing, yielding faster
page load times for users, better resource utilization, and faster
access to the databases on a memcache miss.
##############
台灣同時幾萬人就很了不起了 @@
百萬人環境 存取資料庫將會非常的可怕 , 一般這種流量等級的網站是絕對不會輕易的把資料庫的存取對外的 .
所以 能夠節省 動態網頁 / user 存取動作去接觸到 db 的動作 能快取就盡量快取 ( 最好能沒有 db 就盡量全部從 db doump 出靜態 html )
當然這樣的苦和想法 早在很久以前就大家都玩過了 , 很多做 http 技術多年的朋友們看到這個工具應該都會覺得現在的硬體科技進步太多了 ^^ .
而 這個工具主要是為了 降低 存取 資料庫次數及要求 將 動態網頁 所需要的存取行為快取下來 , 而沿生出來的工具 .
當然 它還有一個好處是可以去避免 sql injection 啦... @@
感想 :
@@ 不過 這麼幹算你狠 ....
我記得多年前 在某一家流量蠻大的公司...
@@ 同時線上人數四萬人 , 會員人數二百多萬..每日點擊次數 幾千萬 , 而且 server 還是 p4 1.x 及 p3 古董 等級的 cpu 而 記憶體 也才 幾百mb 就是屌了.
光是靜態的一個服務就要幾台 做 分散式架構了 ...而且 我們在做這種東西時都只能存在 硬碟 .. ( 記憶體那有這麼大 @@ )
而它提供了 記憶體存取 物件 , 而且可以 分散式的存取 .
現在寫程式的人真幸福... @@ 看到這個 tool 我直接聯想就是... 記憶體真便宜 哈哈哈....
這個玩法 之前和一個南非工程師在閒聊 他們公司是 java 好像也是用類似這樣的工具來做的 在南非有五萬人會同時去存取他們的伺服器...
用這個方法 一台伺服器就可以搞定五萬人同時存取... @@ 只是 記憶體用的超兇... 不過總比 買一堆伺服器好吧 ccc
在無名還沒賣掉前 我在 it home 看到 無名小站用了 幾百台伺服器才搞定 超高流量存取量的問題 ( 我家伺服器還在貨櫃上 厚~ 別跟大家說你用 php 架 services ) .....
看到這篇報導時我覺得當時還真是會亂花錢 , 還好賣掉了 cccc ....
你家網站存取量超級高而且機器用很兇嗎??? 玩看看吧. ^^
範例
In this example, an object is being saved in the cache and then
retrieved back. Object and other non-scalar types are serialized before
saving, so it's impossible to store resources (i.e. connection
identifiers and others) in the cache.
代碼:
<?php
$memcache = new Memcache;
$memcache->connect('localhost', 11211) or die ("Could not connect");
$version = $memcache->getVersion();
echo "Server's version: ".$version."
\n";
$tmp_object = new stdClass;
$tmp_object->str_attr = 'test';
$tmp_object->int_attr = 123;
$memcache->set('key', $tmp_object, false, 10) or die ("Failed to save data at the server");
echo "Store data in the cache (data will expire in 10 seconds)
\n";
$get_result = $memcache->get('key');
echo "Data from the cache:
\n";
var_dump($get_result);
?>代碼:
<?php
$session_save_path = "tcp://$host:$port?persistent=1&weight=2&timeout=2&retry_interval=10, ,tcp://$host:$port ";
ini_set('session.save_handler', 'memcache');
ini_set('session.save_path', $session_save_path);
?>2009年1月5日 星期一
傻瓜相機拍攝教學
 | 數位相機重要三大功能之『測光模式』。 一般來說，測光有三種模式。分別是：平均測光、點測光、中央側光這三種。但不一定每種相機都一定會內建這三種測光模式。當然，最好還是要有比較好啦。 當日正當中，豔陽高照，人物背光『背光就是背後有強光』時，主題會明顯過暗。 這張是以『平均測光』來拍攝。 主題的那郭...大葉子植物，一坨黑黑的，誰知到那是啥阿。 |
 | 分析： 這時候你就能使用『點測光模式』來拍攝了。 將測光模式調到點測光，畫面對著右下方紅點左右的位置，半按快門對焦與測光之後，再將畫面移到你要拍的角度按下快門既可。
|
 | 範例2 前幾年與太太旅遊時拍攝的。 當時因為背光，所以也是利用點測光來測臉部之後拍攝。 使用點測光時，背景一般來說會曝光過渡，造成一遍白茫茫。但這效果，也往往能將主題很清楚明確的表達出來。 |
 | 相反的，我們也能利用點測光來達到一種所謂『剪影』的特殊感覺。 拍攝方法： 將點測光對著光亮之處，半按快門之後再進行畫面構圖。 你看，醬子一來，有種很特殊的味道了吧。 |
| 筆記本： 平均測光：將畫面分割成64等分、甚至254等分之後，相機會去計算每一個格子的明暗度後，平均數值總和來判斷曝光值。拍照時大多使用這模式。 中央測光：以畫面中間約60％～70％來做曝光值計算的一種方式。 |
 | 白平衡： 相機選項幾乎一定會有一個『白平衡』的設定模式。除非你是非常低階的數位相機。 相機大多會內建幾種白平衡模式。例如『AUTO』、『太陽』、『陰天』、『燈泡』、『日光燈』等。比較好一點的，還會有1～2組『自訂白平衡』模式。 簡單說，在戶外出太陽時，白平衡就要調成『太陽』，戶外陰天時，就要調成『陰天』，依此類推。 為何要這樣麻煩呢？那是因為相機構造不像人的眼睛醬子精密與複雜。 不管是在戶外、室內、燈泡下、還是日光燈，我們人眼所看到白色紙張時，我們就知道那是一張白色的紙張，不會誤判『色盲除外』。 相機就沒這麼聰明了『廢話，花100萬元買你一對雙眼你肯挖出來賣嗎』。 所以我們必須告訴相機這些資訊、訊息來幫助相機判斷。 以左邊，下方照片就是標準顏色。 當然，現在相機越做越聰明，大多數場合，使用AUTO模式也不一定會造成相機的誤判。 有時候我們也能利用刻意亂調白平衡來做一些特殊色彩的變化喔。
|
 | |
 |
 |  |
| 1998年，世貿資訊展。筆者故意將白平衡設成『燈泡』模式，拍出左邊比較冰冷的感覺。而右邊則為AUTO白平衡模式。 你看，兩張照片感覺有差吧！ | |
 | 1998年攝於筆者辦公室。 有沒有感覺到很怪異的偏綠色色調？ 現在室內燈源太複雜啦。明明都是日光燈管，但廠牌、型號不同，其顏色都不一樣。 這時候，若相機有『自設白平衡』功能，只要隨便找一張白紙，就能立即做設定。 可惜當時筆者的相機沒有這功能，所以辦公室內所拍的照片，都是這個怪色調。 |
 | 在光線不夠明亮的時候，相機為了達到足夠的光線，會降低快門的速度。 快門一放慢，若主題晃動或者拍攝者的身體、手也晃動，那麼拍出來的效果就是這個樣子。 感謝我兒子286友情客串。 |
 | 窩喔，那怎辦阿，拍得那樣模糊，有拍跟沒拍也沒甚麼兩樣了耶！ 沒關係，教你一招『必殺技』。 |
 | 挖咧....別亂教啦486，要是學你這一招，我不被我家人打死才怪... 好啦好啦，講正經的。 若光線不足，你可以移一展檯燈過來，醬子不就行啦。 |
 | 或者等白天再拍不會喔。 不要不要...人家就是要在晚上拍攝啦。
|
 | 其實你可以開啟閃光燈來拍。 但若有些場合不能開啟閃當燈，又或者拍小寶寶怕閃燈會傷害寶寶眼睛，你可以將ISO值調高一些。 這是才是這單元要講的重點啦！ 大多數位相機值能從100調到400。數值越高，感光度越高。 但，有部分相機，若ISO值太高，畫面的顆粒會很粗糙喔。 所以關於這點，挑選相機時要問問口碑了。 |
2002.08.27
光影魔術手使用說明
2007.08.20 【分享】nEO 撕邊修改 | mscraft |
2007.08.08 【分享】nEO 撕邊應用 | mscraft |
2007.07.23 【分享】nEO 撕邊下載 | mscraft |
2007.07.16 【分享】nEO 撕邊邊框 | mscraft |
2007.07.02 【分享】nEO 素材站 | mscraft |
2007.06.25 【教學】nEO 嚴重白平衡 | mscraft |
2007.06.04 【教學】nEO 浮水印（三） | mscraft |
2007.04.16 【教學】nEO 自由文字圖層 | mscraft |
2007.04.09 【分享】nEO 多圖邊框論壇 | mscraft |
2007.03.26 【教學】nEO 裁剪虛化（二） | mscraft |
2007.03.21 【教學】nEO 裁剪填充（一） | mscraft |
2007.03.12 【分享】nEO 新版上市 | mscraft |
2007.03.05 【分享】nEO 新版0.24 | mscraft |
2006.12.18 【分享】nEO 繁體中文 0.23 | mscraft |
2006.11.29 【教學】nEO 油畫效果 II | mscraft |
2006.11.24 【教學】nEO 油畫效果 | mscraft |
2006.10.02 【分享】nEO 開發中的 0.23 | mscraft |
2006.09.29 【教學】nEO 花樣邊框 INI | mscraft |
2006.09.25 【下載】花樣邊框 | mscraft |
2006.08.28 【分享】nEO 花樣邊框下載 | mscraft |
2006.08.14 【分享】nEO 官方論壇 | mscraft |
2006.08.11 【教學】nEO 邊框工廠 | mscraft |
2006.08.09 【分享】光影魔術手 0.22 | mscraft |
2006.07.21 【下載】撕邊邊框（四） | mscraft |
2006.07.07 【下載】光影魔術手0.21版 | mscraft |
2006.06.23 【下載】nEO 邊框下載 | mscraft |
2006.06.05 【下載】撕邊邊框下載 總整理 | mscraft |
2006.05.15 【分享】nEO 撕邊邊框下載（三） | mscraft |
2006.05.12 【下載】nEO 撕邊邊框（二） | mscraft |
2006.05.11 【下載】nEO 撕邊邊框（一） | mscraft |
2006.05.03 【教學】nEO 郵寄戳章 ＆ 浮水印（十） | mscraft |
2006.05.02 【教學】nEO 撕邊邊框 DIY（九） | mscraft |
2006.04.28 【教學】nEO 花樣邊框DIY（八） | mscraft |
2006.04.27 【教學】nEO 撕邊邊框（七） | mscraft |
2006.04.26 【教學】nEO 輕鬆與花樣邊框（六） | mscraft |
2006.04.21 【教學】nEO 製作多圖組合（五） | mscraft |
2006.04.20 【教學】nEO 自動處理（四） | mscraft |
2006.04.19 【教學】nEO 白平衡（三） | mscraft |
2006.04.18 【教學】nEO 曝光調整（二） | mscraft |
2006.04.17 【教學】nEO 檢視縮放（一） | mscraft |
2006.03.30 【教學】nEO 0.2 繁體中文版 | mscraft |
2006.03.28 【分享】光影魔術手 |
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