Skip to content

Fix: Bedrock aspect ratio rejection for form PDFs #45

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Nishit24113 wants to merge 1 commit into
base: main
Choose a base branch
from
Open

Fix: Bedrock aspect ratio rejection for form PDFs #45

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
60 changes: 54 additions & 6 deletions alt-text-generator-container/alt_text_generator.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,42 @@ function sleep(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}

const MAX_ASPECT_RATIO = 20;

function getImageDimensions(buffer) {
try {
if (buffer[0] === 0x89 && buffer[1] === 0x50 && buffer[2] === 0x4E && buffer[3] === 0x47) {
const width = buffer.readUInt32BE(16);
const height = buffer.readUInt32BE(20);
return { width, height };
}
if (buffer[0] === 0xFF && buffer[1] === 0xD8) {
let offset = 2;
while (offset < buffer.length - 1) {
if (buffer[offset] !== 0xFF) break;
const marker = buffer[offset + 1];
if (marker === 0xC0 || marker === 0xC2) {
const height = buffer.readUInt16BE(offset + 5);
const width = buffer.readUInt16BE(offset + 7);
return { width, height };
}
const segmentLength = buffer.readUInt16BE(offset + 2);
offset += 2 + segmentLength;
}
}
return null;
} catch (e) {
return null;
}
}

function isAspectRatioValid(dimensions) {
if (!dimensions || !dimensions.width || !dimensions.height) return true;
const { width, height } = dimensions;
const ratio = Math.max(width / height, height / width);
return ratio <= MAX_ASPECT_RATIO;
}


/**
* Invokes the Bedrock AI model to generate alt text for a given image.
Expand Down Expand Up @@ -492,6 +528,8 @@ async function startProcess() {
logger.info(`Filename: ${filebasename} | imageObjects: ${imageObjects}`);
logger.info(`Filename: ${filebasename} | Total images to process: ${imageObjects.length}`);

let skippedCount = 0;

for (const imageObject of imageObjects) {
try {
const getObjectParams = {
Expand All @@ -502,7 +540,7 @@ async function startProcess() {
logger.info(`Filename: ${filebasename} | Image Object Bucketname: ${bucketName}`);
const command = new GetObjectCommand(getObjectParams);
const { Body } = await s3Client.send(command);

// Stream the body contents to a buffer
const chunks = [];
await pipeline(Body, async function* (source) {
Expand All @@ -511,6 +549,16 @@ async function startProcess() {
}
});
const fileBuffer = Buffer.concat(chunks);

const dimensions = getImageDimensions(fileBuffer);
if (dimensions && !isAspectRatioValid(dimensions)) {
skippedCount++;
const altText = "Decorative element";
combinedResults[imageObject.id] = altText;
logger.info(`Filename: ${filebasename} | Skipping image ${imageObject.id} - aspect ratio ${Math.max(dimensions.width/dimensions.height, dimensions.height/dimensions.width).toFixed(1)}:1 exceeds ${MAX_ASPECT_RATIO}:1 limit (${dimensions.width}x${dimensions.height})`);
continue;
}

const localFilePath = path.join(__dirname, `${imageObject.path.split('/').pop()}`);
logger.info(`Filename: ${filebasename} | Local File Path: ${localFilePath}`);
fs_1.writeFileSync(localFilePath, fileBuffer);
Expand All @@ -519,23 +567,23 @@ async function startProcess() {
logger.info(`Filename: ${filebasename} | Response:${response}`);
Object.assign(combinedResults, JSON.parse(response));
successCount++;
logger.info(`Filename: ${filebasename} | Alt text generation succeeded for image ${imageObject.id} (${successCount} succeeded, ${failureCount} failed)`);
logger.info(`Filename: ${filebasename} | Alt text generation succeeded for image ${imageObject.id} (${successCount} succeeded, ${failureCount} failed, ${skippedCount} skipped)`);
} catch (error) {
failureCount++;
logger.error(`Filename: ${filebasename} | Alt text generation failed for image ${imageObject.id}: ${error.message || error}`);
logger.info(`Filename: ${filebasename} | Progress: ${successCount} succeeded, ${failureCount} failed`);
logger.info(`Filename: ${filebasename} | Progress: ${successCount} succeeded, ${failureCount} failed, ${skippedCount} skipped`);
}
await sleep(2000);
}

// Check if we have any images and if all of them failed
if (imageObjects.length > 0 && successCount === 0) {
// Only fail if all images failed AND none were skipped (skipped images got default alt text)
if (imageObjects.length > 0 && successCount === 0 && skippedCount === 0) {
logger.error(`Filename: ${filebasename} | All ${failureCount} alt text generation requests failed - likely due to throttling or Bedrock API issues`);
logger.error(`File: ${filebasename}, Status: Failed in second ECS task - All Bedrock requests failed`);
process.exit(1);
}

logger.info(`Filename: ${filebasename} | Alt text generation complete: ${successCount} succeeded, ${failureCount} failed out of ${imageObjects.length} images`);
logger.info(`Filename: ${filebasename} | Alt text generation complete: ${successCount} succeeded, ${failureCount} failed, ${skippedCount} skipped (bad aspect ratio) out of ${imageObjects.length} images`);

let defaultText = "No text available";

Expand Down