model: support for mistral-small in the ollama runner

Mistral is a popular research lab making open source models. This updates
the forward pass of llama architecture models to support both llama models
and mistral models by accounting for additional metadata present in mistral
models, and finding the correct dimensions for the output projection.

model/models/mistral3/imageproc.go

@@ -0,0 +1,56 @@
+package mistral3
+
+import (
+	"image"
+	_ "image/jpeg"
+	_ "image/png"
+	"math"
+
+	"github.com/ollama/ollama/fs"
+	"github.com/ollama/ollama/model/imageproc"
+)
+
+type ImageProcessor struct {
+	imageSize   int
+	patchSize   int
+	numChannels int
+	longestEdge int
+}
+
+func newImageProcessor(c fs.Config) ImageProcessor {
+	return ImageProcessor{
+		imageSize:   int(c.Uint("vision.image_size", 1540)),
+		patchSize:   int(c.Uint("vision.patch_size", 14)),
+		numChannels: int(c.Uint("vision.num_channels", 3)),
+		longestEdge: int(c.Uint("vision.longest_edge", 1540)),
+	}
+}
+
+// ProcessImage prepares an image for the vision model by:
+// 1. Compositing transparent images
+// 2. Resizing to fit model constraints while preserving aspect ratio
+// 3. Normalizing pixel values
+// Returns normalized image data and the final size in pixels
+func (p *ImageProcessor) ProcessImage(img image.Image) ([]float32, image.Point, error) {
+	img = imageproc.Composite(img)
+
+	size := img.Bounds().Size()
+	ratio := max(float64(size.Y)/float64(p.longestEdge), float64(size.X)/float64(p.longestEdge))
+	if ratio > 1.0 {
+		size = image.Point{
+			int(math.Floor(float64(size.X) / ratio)),
+			int(math.Floor(float64(size.Y) / ratio)),
+		}
+	}
+
+	patchesX := (size.X-1)/p.patchSize + 1
+	patchesY := (size.Y-1)/p.patchSize + 1
+	size = image.Point{
+		patchesX * p.patchSize,
+		patchesY * p.patchSize,
+	}
+
+	img = imageproc.Resize(img, size, imageproc.ResizeBilinear)
+	data := imageproc.Normalize(img, imageproc.ClipDefaultMean, imageproc.ClipDefaultSTD, true, true)
+	return data, size, nil
+}