The DiffALL Blog
Practical guides on image and video quality metrics, compression, and media comparison workflows.
What Is a Spectrogram? How to Read One (With Examples)
A plain-English guide to spectrograms — what the axes mean, what a mel spectrogram is, and how to use a spectrogram difference to find where two audio files diverge.
Quality MetricsPSNR vs SSIM — Which Metric Should You Use?
PSNR and SSIM are the two most common image quality metrics, and they often disagree. What each measures, when each is right, and how to read a conflict.
Image ComparisonHow to Compare Before and After Photos
Compare before and after photos and measure exactly what changed — with a side-by-side view, a difference heatmap, and a 0-100 similarity score. Free, no install.
Text & DataHow to Compare Two CSV Files Online
Compare two CSV files and instantly see which rows and values changed — added, removed, or modified — without wrestling with spreadsheets. Free, no install.
Text & DataHow to Compare Two Text Files Online
Compare two text files and see every difference line by line and character by character — with a similarity score. Free, no install, works by paste or upload.
Text & DataHow to Compare Two XML Files and See What Changed
Compare two XML files online and find every changed element, attribute and value, ignoring formatting noise. Free XML compare, no install.
Image ComparisonHow to Find Duplicate or Near-Duplicate Images
Tell whether two images are true duplicates, near-duplicates or genuinely different, with a similarity score and a difference heatmap. Free, no install.
Image ComparisonHow to Spot Edited or Tampered Images
Compare a suspect image against the original and reveal every edited region: retouching, added or removed objects, splices, in a pixel difference heatmap.
Video QualityWhat is VMAF and How to Use It for Video Quality
What VMAF means, what Netflix's video quality metric measures, how to read a VMAF score, and how it compares with PSNR and SSIM.
Subtitles & TextWord Error Rate (WER) Explained — and How to Measure It
What Word Error Rate means, how it's calculated, what counts as a good score, and how to measure WER between two transcripts or subtitle files. Free, no install.
Video QAHow to Compare Two Videos Frame by Frame
Compare two videos frame by frame online and see exactly where they differ: dropped frames, compression loss, colour shifts, with a synced heatmap player.
QA & TestingHow to Compare Two Screenshots and Spot Every Difference
Compare two screenshots online and see every pixel that changed: layout shifts, colour changes, missing elements, with a heatmap and a similarity score.