SubtitleEdit/subtitleedit · error · Exception

Could not determine original image dimensions.

Error message

Could not determine original image dimensions.

What it means

Thrown by Lens.ScanByBitmap when the supplied SKBitmap has a Width or Height of 0. A zero-dimension bitmap cannot be processed or uploaded (and cannot be resized), so the method aborts before any work. This guards against uninitialized or empty bitmaps reaching the OCR pipeline.

Source

Thrown at src/ui/Logic/Ocr/GoogleLens/Lens.cs:38

        {
            Console.WriteLine($"Lens constructor expects a dictionary, got {config.GetType()}");
            config = new Dictionary<string, object>();
        }
    }

    public async Task<LensResult> ScanByBitmap(SKBitmap bitmap, string twoLetterLanguageCode)
    {
        if (bitmap == null)
        {
            throw new ArgumentNullException(nameof(bitmap));
        }

        var originalWidth = bitmap.Width;
        var originalHeight = bitmap.Height;

        if (originalWidth == 0 || originalHeight == 0)
        {
            throw new Exception("Could not determine original image dimensions.");
        }

        var bitmapToProcess = bitmap;
        var finalMime = "image/png";

        const int MAX_DIMENSION = 1200;

        // Only process if absolutely necessary
        if (originalWidth > MAX_DIMENSION || originalHeight > MAX_DIMENSION)
        {
            // Calculate new dimensions maintaining aspect ratio
            float ratio = Math.Min((float)MAX_DIMENSION / originalWidth, (float)MAX_DIMENSION / originalHeight);
            int newWidth = (int)(originalWidth * ratio);
            int newHeight = (int)(originalHeight * ratio);

            using var resized = bitmap.Resize(new SKImageInfo(newWidth, newHeight), new SKSamplingOptions(SKFilterMode.Linear, SKMipmapMode.Linear));
            if (resized == null)
            {

View on GitHub (pinned to 17a9f07487)

Solutions

  1. Null- and dimension-check the bitmap before calling ScanByBitmap (bitmap != null && bitmap.Width > 0 && bitmap.Height > 0).
  2. Validate the source of the bitmap (decode result) and reject empties upstream.
  3. Ensure the bitmap is created from valid SKImageInfo with non-zero dimensions.
  4. Surface a user-facing 'invalid image' message instead of letting the exception propagate.

Example fix

// before
var result = await lens.ScanByBitmap(bitmap, lang);

// after
if (bitmap == null || bitmap.Width == 0 || bitmap.Height == 0) throw new ArgumentException("Invalid bitmap");
var result = await lens.ScanByBitmap(bitmap, lang);
Defensive patterns

Strategy: validation

Validate before calling

if (bitmap == null) throw new ArgumentNullException(nameof(bitmap));
if (bitmap.Width == 0 || bitmap.Height == 0) throw new ArgumentException("Bitmap has zero dimensions");
var r = await lens.ScanByBitmap(bitmap, lang);

Type guard

static bool IsValidBitmap(SKBitmap b) => b != null && b.Width > 0 && b.Height > 0;

Try / catch

try { var r = await lens.ScanByBitmap(bitmap, lang); }
catch (Exception ex) when (ex.Message.Contains("original image dimensions")) { /* notify user */ }

Prevention

When it happens

Trigger: Passing a default/uninitialized SKBitmap, a bitmap from a failed decode that still reports 0x0, or a programmatically created bitmap whose info had zero dimensions.

Common situations: A prior SKBitmap.Decode returned an empty bitmap that was not null-checked; constructing SKBitmap with a zero-size SKImageInfo; a bitmap whose underlying native object was disposed/empty.

Related errors

AI-assisted analysis of SubtitleEdit/subtitleedit@17a9f07487 (2026-08-13). Data as JSON: /api/errors/953ede0f45e187ac. Report an issue: GitHub.