Tim Mattison

Hardcore tech

Image Metadata Extraction With AWS Lambda and Java

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I just started a repo to keep track of my AWS Lambda (Java) experiments. The first experiment is using Java to extract metadata from an uploaded image. It is a bit unconventional because it doesn’t use S3 but that was done to make the setup simpler. Here’s how you can play around with the metadata extractor…

This tutorial will walk you through getting the metadata extractor set up, calling it, and then tearing it down. The commands in this tutorial assume you are in the metadata-extractor directory.

NOTE: Do not forget to do step 5 – “Tear down your function” – or you may be sorry!

Step 1: Build the JAR

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$ mvn clean compile test package

You should get a BUILD SUCCESS if everything worked.

Step 2: Create the Lambda function

Navigate to step 2 of the AWS Lambda creation process (step 1 is selecting a blueprint/template which we do not want to do).

  • Name your function metadata-extractor
  • Enter a description if you want
  • Set the runtime to Java 8
  • Select Upload a ZIP file (it should be selected by default)
  • Click “Upload” and select the file metadata-extractor-1.0-SNAPSHOT-jar-with-dependencies.jar from the metadata-extractor/target directory
  • Set the handler to com.timmattison.ImageHandler::handleRequest
  • Set the role to Basic execution role or lambda_basic_execution, whichever exists. NOTE: If you have popups disabled this may continually tell you that you didn’t fill the field in. You MUST enable popups to get this to work.
  • Set the memory to 128 MB
  • Set the timeout to 5 seconds
  • Click Next
  • Click Create function

Step 3: Create a public endpoint that you can test

You should now be on a screen that says “Lambda > Functions > metadata-extractor”. There should be five tabs visible. They are “Code”, “Configuration”, “Event sources”, “API endpoints”, “Monitoring”.

  • Click on the API endpoints tab
  • Click Add API endpoint
  • Set API name to LambdaMicroservice
  • Set Resource name to metadata-extractor
  • Set Method to POST
  • Set Deployment stage to prod
  • Set Security to Open (we will destroy this service later so it can’t be abused)
  • Click Add API endpoint

You should now see a table with three columns. The rightmost column “API endpoint URL” contains the URL for the endpoint you just created. It should be similar to this:

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https://xxxxxxxxxxx.execute-api.us-east-1.amazonaws.com/prod/metadata-extractor

Copy that somewhere where you can get to it later.

Step 4: Upload an image to the URL

Now you’re ready to upload an image to the URL you just created. Lambda is expecting data in JSON format, not binary uploads. We do something a bit hacky to make our lives easier here. We take the image, convert it to base64, and put it into a JSON object before we upload it. This is done with the Python script called convert-image-to-json.py. Assuming your image is called myimage.jpg and your URL is https://xxxxxxxxxxx.execute-api.us-east-1.amazonaws.com/prod/metadata-extractor you would do this to upload your image.

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$ ./convert-image-to-json.py myimage.jpg | curl -X POST https://xxxxxxxxxxx.execute-api.us-east-1.amazonaws.com/prod/metadata-extractor -d@-

If your image contains any metadata you’ll get a response that contains a bunch of interesting info. Here are the results from one PNG I had lying around:

“[PNG-IHDR] Image Width – 332, [PNG-IHDR] Image Height – 48, [PNG-IHDR] Bits Per Sample – 8, [PNG-IHDR] Color Type – True Color with Alpha, [PNG-IHDR] Compression Type – Deflate, [PNG-IHDR] Filter Method – Adaptive, [PNG-IHDR] Interlace Method – No Interlace, [PNG-iCCP] ICC Profile Name – ICC Profile, [ICC Profile] Profile Size – 1960, [ICC Profile] CMM Type – appl, [ICC Profile] Version – 2.2.0, [ICC Profile] Class – Display Device, [ICC Profile] Color space – RGB , [ICC Profile] Profile Connection Space – XYZ , [ICC Profile] Profile Date/Time – Wed Mar 25 11:26:11 UTC 2009, [ICC Profile] Signature – acsp, [ICC Profile] Primary Platform – Apple Computer, Inc., [ICC Profile] Device manufacturer – appl, [ICC Profile] XYZ values – 0.9642029 1.0 0.8249054, [ICC Profile] Tag Count – 11, [ICC Profile] Profile Description – Generic RGB Profile, [ICC Profile] Apple Multi-language Profile Name – 30 skSK(Všeobecný RGB profil) hrHR(Generički RGB profil) caES(Perfil RGB genèric) ptBR(Perfil RGB Genérico) ukUA(Загальний профайл RGB) frFU(Profil générique RVB) zhTW(通用 RGB 色彩描述) itIT(Profilo RGB generico) nbNO(Generisk RGB-profil) koKR(일반 RGB 프로파일) csCZ(Obecný RGB profil) heIL(פרופיל RGB כללי) deDE(Allgemeines RGB-Profil) huHU(Általános RGB profil) svSE(Generisk RGB-profil) zhCN(普通 RGB 描述文件) jaJP(一般 RGB プロファイル) roRO(Profil RGB generic) elGR(Γενικό προφίλ RGB) ptPO(Perfil RGB genérico) nlNL(Algemeen RGB-profiel) esES(Perfil RGB genérico) thTH(โปรไฟล์ RGB ทั่วไป) trTR(Genel RGB Profili) fiFI(Yleinen RGB-profiili) plPL(Uniwersalny profil RGB) ruRU(Общий профиль RGB) arEG(ملف تعريف RGB العام) enUS(Generic RGB Profile) daDK(Generel RGB-beskrivelse), [ICC Profile] Copyright – Copyright 2007 Apple Inc., all rights reserved., [ICC Profile] Media White Point – (0.95047, 1.0, 1.0890961), [ICC Profile] Red Colorant – (0.45429993, 0.24191284, 0.014892578), [ICC Profile] Green Colorant – (0.35334778, 0.67362976, 0.09063721), [ICC Profile] Blue Colorant – (0.15664673, 0.0844574, 0.719574), [ICC Profile] Red TRC – 0.0070344, [ICC Profile] Chromatic Adaptation – sf32(0x73663332): 44 bytes, [ICC Profile] Blue TRC – 0.0070344, [ICC Profile] Green TRC – 0.0070344” “`

Step 5: Tear down your function

The function you’ve created is now publicly accessible. That means that if someone finds it they can hit it and start costing you real money. It is in your best interest to shut this function down when you’re done with it.

  • Click Actions
  • Click Delete function
  • Click Delete

You’re done! Have fun!

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