Manual Graph Digitizer (1-file HTML)

1) Image & Axis

Which axis to read?

X-axis (horizontal) Y-axis (vertical)

Assumes the chart axes are horizontal/vertical (no rotation/keystone).

2) Calibration (2 points + real values)

Value at point A

Value at point B

Not calibrated

We map pixel → value by linear interpolation along the selected axis. Up/down flips are handled automatically by the two reference points.

3) Measure (start → end)

4) Export

Canvas

Zoom 100% · Offset (0, 0)

Tips: Hold Space to pan temporarily. Use 1 to start calibration, 2 to start measuring, F to fit, 1 (key) to set zoom 100%.

Measurements

Series	Axis	Start (pxX, pxY)	End (pxX, pxY)	Start value	End value	Value Δ	Pixel Δ	Timestamp

There was feedback that the graph OCR and reading accuracy of ChatGPT and Gemini were not reliable, so I created this website. / Chat GPTやGeminiのグラフのOCR、読み取りが正確ではないという感想があったので、このサイトを作成しました。/由于有人反馈ChatGPT和Gemini的图表OCR和读取精度不够准确，所以我创建了这个网站。/Hubo comentarios de que el OCR y la lectura de gráficos de ChatGPT y Gemini no eran precisos, así que creé este sitio web.