Support half float file format storage for Multilayer EXR

Quite straightforward implementation -- all the conversion magic is
happening in IMB_exr_write_channels() and remained changes are only
needed to pass information whether channels is to be converted to
half float or not.

Regular file output will use full-float for Z pass, which matches
behavior of the single layer EXR files. But when saving happens
with File Output node then all the passes are respecting half float
settings because it's not possible to distinguish whether we're
saving Z pass or not.

Reviewers: juicyfruit, campbellbarton

Reviewed By: campbellbarton

Subscribers: maxon, effstops, fsiddi

Differential Revision: https://developer.blender.org/D1353

10 files changed, 117 insertions, 47 deletions

diff --git a/source/blender/blenkernel/intern/image.c b/source/blender/blenkernel/intern/image.c
index 90aa09430ae..451ab43367b 100644
--- a/source/blender/blenkernel/intern/image.c
+++ b/source/blender/blenkernel/intern/image.c
@@ -1400,7 +1400,7 @@ char BKE_imtype_valid_depths(const char imtype)
 		case R_IMF_IMTYPE_OPENEXR:
 			return R_IMF_CHAN_DEPTH_16 | R_IMF_CHAN_DEPTH_32;
 		case R_IMF_IMTYPE_MULTILAYER:
-			return R_IMF_CHAN_DEPTH_32;
+			return R_IMF_CHAN_DEPTH_16 | R_IMF_CHAN_DEPTH_32;
 		/* eeh, cineon does some strange 10bits per channel */
 		case R_IMF_IMTYPE_DPX:
 			return R_IMF_CHAN_DEPTH_8 | R_IMF_CHAN_DEPTH_10 | R_IMF_CHAN_DEPTH_12 | R_IMF_CHAN_DEPTH_16;
diff --git a/source/blender/compositor/nodes/COM_OutputFileNode.cpp b/source/blender/compositor/nodes/COM_OutputFileNode.cpp
index acd2602e216..42805d1ff37 100644
--- a/source/blender/compositor/nodes/COM_OutputFileNode.cpp
+++ b/source/blender/compositor/nodes/COM_OutputFileNode.cpp
@@ -47,18 +47,21 @@ void OutputFileNode::convertToOperations(NodeConverter &converter, const Composi
 		 */
 		return;
 	}
-	
+
 	if (storage->format.imtype == R_IMF_IMTYPE_MULTILAYER) {
+		const bool use_half_float = (storage->format.depth == R_IMF_CHAN_DEPTH_16);
 		/* single output operation for the multilayer file */
 		OutputOpenExrMultiLayerOperation *outputOperation;
 
 		if (is_multiview && storage->format.views_format == R_IMF_VIEWS_MULTIVIEW) {
 			outputOperation = new OutputOpenExrMultiLayerMultiViewOperation(
-			        context.getRenderData(), context.getbNodeTree(), storage->base_path, storage->format.exr_codec, context.getViewName());
+			        context.getRenderData(), context.getbNodeTree(), storage->base_path,
+			        storage->format.exr_codec, use_half_float, context.getViewName());
 		}
 		else {
 			outputOperation = new OutputOpenExrMultiLayerOperation(
-		          context.getRenderData(), context.getbNodeTree(), storage->base_path, storage->format.exr_codec, context.getViewName());
+		          context.getRenderData(), context.getbNodeTree(), storage->base_path,
+		          storage->format.exr_codec, use_half_float, context.getViewName());
 		}
 		converter.addOperation(outputOperation);
 
diff --git a/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.cpp b/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.cpp
index e89af9cc15b..7786359c06a 100644
--- a/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.cpp
+++ b/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.cpp
@@ -74,7 +74,7 @@ void *OutputOpenExrSingleLayerMultiViewOperation::get_handle(const char *filenam
 				continue;
 
 			IMB_exr_add_view(exrhandle, srv->name);
-			add_exr_channels(exrhandle, NULL, this->m_datatype, srv->name, width, NULL);
+			add_exr_channels(exrhandle, NULL, this->m_datatype, srv->name, width, false, NULL);
 		}
 
 		BLI_make_existing_file(filename);
@@ -108,7 +108,8 @@ void OutputOpenExrSingleLayerMultiViewOperation::deinitExecution()
 		        (this->m_rd->scemode & R_EXTENSION) != 0, true, NULL);
 
 		exrhandle = this->get_handle(filename);
-		add_exr_channels(exrhandle, NULL, this->m_datatype, this->m_viewName, width, this->m_outputBuffer);
+		add_exr_channels(exrhandle, NULL, this->m_datatype, this->m_viewName, width,
+		                 this->m_format->depth == R_IMF_CHAN_DEPTH_16, this->m_outputBuffer);
 
 		/* memory can only be freed after we write all views to the file */
 		this->m_outputBuffer = NULL;
@@ -130,8 +131,9 @@ void OutputOpenExrSingleLayerMultiViewOperation::deinitExecution()
 /************************************  OpenEXR Multilayer Multiview *****************************************/
 
 OutputOpenExrMultiLayerMultiViewOperation::OutputOpenExrMultiLayerMultiViewOperation(
-        const RenderData *rd, const bNodeTree *tree, const char *path, char exr_codec, const char *viewName)
-    : OutputOpenExrMultiLayerOperation(rd, tree, path, exr_codec, viewName)
+        const RenderData *rd, const bNodeTree *tree, const char *path,
+        char exr_codec, bool exr_half_float, const char *viewName)
+    : OutputOpenExrMultiLayerOperation(rd, tree, path, exr_codec, exr_half_float, viewName)
 {
 }
 
@@ -162,7 +164,8 @@ void *OutputOpenExrMultiLayerMultiViewOperation::get_handle(const char *filename
 			IMB_exr_add_view(exrhandle, srv->name);
 
 			for (unsigned int i = 0; i < this->m_layers.size(); ++i)
-				add_exr_channels(exrhandle, this->m_layers[i].name, this->m_layers[i].datatype, srv->name, width, NULL);
+				add_exr_channels(exrhandle, this->m_layers[i].name, this->m_layers[i].datatype,
+				                 srv->name, width, this->m_exr_half_float, NULL);
 		}
 
 		BLI_make_existing_file(filename);
@@ -197,7 +200,8 @@ void OutputOpenExrMultiLayerMultiViewOperation::deinitExecution()
 		exrhandle = this->get_handle(filename);
 
 		for (unsigned int i = 0; i < this->m_layers.size(); ++i)
-			add_exr_channels(exrhandle, this->m_layers[i].name, this->m_layers[i].datatype, this->m_viewName, width, this->m_layers[i].outputBuffer);
+			add_exr_channels(exrhandle, this->m_layers[i].name, this->m_layers[i].datatype, this->m_viewName,
+			                 width, this->m_exr_half_float, this->m_layers[i].outputBuffer);
 
 		for (unsigned int i = 0; i < this->m_layers.size(); ++i) {
 			/* memory can only be freed after we write all views to the file */
@@ -269,7 +273,8 @@ void OutputStereoOperation::deinitExecution()
 		float *buf = this->m_outputBuffer;
 
 		/* populate single EXR channel with view data */
-		IMB_exr_add_channel(exrhandle, NULL, this->m_name, this->m_viewName, 1, this->m_channels * width * height, buf);
+		IMB_exr_add_channel(exrhandle, NULL, this->m_name, this->m_viewName, 1, this->m_channels * width * height, buf,
+		                    this->m_format->depth == R_IMF_CHAN_DEPTH_16);
 
 		this->m_imageInput = NULL;
 		this->m_outputBuffer = NULL;
diff --git a/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.h b/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.h
index 25716fdb9e1..0e3cde66897 100644
--- a/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.h
+++ b/source/blender/compositor/operations/COM_OutputFileMultiViewOperation.h
@@ -51,7 +51,8 @@ public:
 class OutputOpenExrMultiLayerMultiViewOperation : public OutputOpenExrMultiLayerOperation {
 private:
 public:
-	OutputOpenExrMultiLayerMultiViewOperation(const RenderData *rd, const bNodeTree *tree, const char *path, char exr_codec, const char *viewName);
+	OutputOpenExrMultiLayerMultiViewOperation(const RenderData *rd, const bNodeTree *tree, const char *path,
+	                                          char exr_codec, bool exr_half_float, const char *viewName);
 
 	void *get_handle(const char *filename);
 	void deinitExecution();
diff --git a/source/blender/compositor/operations/COM_OutputFileOperation.cpp b/source/blender/compositor/operations/COM_OutputFileOperation.cpp
index b99b0d5b875..fdf5a0b48cf 100644
--- a/source/blender/compositor/operations/COM_OutputFileOperation.cpp
+++ b/source/blender/compositor/operations/COM_OutputFileOperation.cpp
@@ -40,23 +40,24 @@ extern "C" {
 #  include "IMB_imbuf_types.h"
 }
 
-void add_exr_channels(void *exrhandle, const char *layerName, const DataType datatype, const char *viewName, const size_t width, float *buf)
+void add_exr_channels(void *exrhandle, const char *layerName, const DataType datatype,
+                      const char *viewName, const size_t width, bool use_half_float, float *buf)
 {
 	/* create channels */
 	switch (datatype) {
 		case COM_DT_VALUE:
-			IMB_exr_add_channel(exrhandle, layerName, "V", viewName, 1, width, buf ? buf : NULL);
+			IMB_exr_add_channel(exrhandle, layerName, "V", viewName, 1, width, buf ? buf : NULL, use_half_float);
 			break;
 		case COM_DT_VECTOR:
-			IMB_exr_add_channel(exrhandle, layerName, "X", viewName, 3, 3 * width, buf ? buf : NULL);
-			IMB_exr_add_channel(exrhandle, layerName, "Y", viewName, 3, 3 * width, buf ? buf + 1 : NULL);
-			IMB_exr_add_channel(exrhandle, layerName, "Z", viewName, 3, 3 * width, buf ? buf + 2 : NULL);
+			IMB_exr_add_channel(exrhandle, layerName, "X", viewName, 3, 3 * width, buf ? buf : NULL, use_half_float);
+			IMB_exr_add_channel(exrhandle, layerName, "Y", viewName, 3, 3 * width, buf ? buf + 1 : NULL, use_half_float);
+			IMB_exr_add_channel(exrhandle, layerName, "Z", viewName, 3, 3 * width, buf ? buf + 2 : NULL, use_half_float);
 			break;
 		case COM_DT_COLOR:
-			IMB_exr_add_channel(exrhandle, layerName, "R", viewName, 4, 4 * width, buf ? buf : NULL);
-			IMB_exr_add_channel(exrhandle, layerName, "G", viewName, 4, 4 * width, buf ? buf + 1 : NULL);
-			IMB_exr_add_channel(exrhandle, layerName, "B", viewName, 4, 4 * width, buf ? buf + 2 : NULL);
-			IMB_exr_add_channel(exrhandle, layerName, "A", viewName, 4, 4 * width, buf ? buf + 3 : NULL);
+			IMB_exr_add_channel(exrhandle, layerName, "R", viewName, 4, 4 * width, buf ? buf : NULL, use_half_float);
+			IMB_exr_add_channel(exrhandle, layerName, "G", viewName, 4, 4 * width, buf ? buf + 1 : NULL, use_half_float);
+			IMB_exr_add_channel(exrhandle, layerName, "B", viewName, 4, 4 * width, buf ? buf + 2 : NULL, use_half_float);
+			IMB_exr_add_channel(exrhandle, layerName, "A", viewName, 4, 4 * width, buf ? buf + 3 : NULL, use_half_float);
 			break;
 		default:
 			break;
@@ -227,13 +228,15 @@ OutputOpenExrLayer::OutputOpenExrLayer(const char *name_, DataType datatype_, bo
 }
 
 OutputOpenExrMultiLayerOperation::OutputOpenExrMultiLayerOperation(
-        const RenderData *rd, const bNodeTree *tree, const char *path, char exr_codec, const char *viewName)
+        const RenderData *rd, const bNodeTree *tree, const char *path,
+        char exr_codec, bool exr_half_float, const char *viewName)
 {
 	this->m_rd = rd;
 	this->m_tree = tree;
 	
 	BLI_strncpy(this->m_path, path, sizeof(this->m_path));
 	this->m_exr_codec = exr_codec;
+	this->m_exr_half_float = exr_half_float;
 	this->m_viewName = viewName;
 }
 
@@ -284,7 +287,8 @@ void OutputOpenExrMultiLayerOperation::deinitExecution()
 			if (!layer.imageInput)
 				continue; /* skip unconnected sockets */
 			
-			add_exr_channels(exrhandle, this->m_layers[i].name, this->m_layers[i].datatype, "", width, this->m_layers[i].outputBuffer);
+			add_exr_channels(exrhandle, this->m_layers[i].name, this->m_layers[i].datatype, "", width,
+			                 this->m_exr_half_float, this->m_layers[i].outputBuffer);
 		}
 		
 		/* when the filename has no permissions, this can fail */
diff --git a/source/blender/compositor/operations/COM_OutputFileOperation.h b/source/blender/compositor/operations/COM_OutputFileOperation.h
index 58ebf055583..93468977a66 100644
--- a/source/blender/compositor/operations/COM_OutputFileOperation.h
+++ b/source/blender/compositor/operations/COM_OutputFileOperation.h
@@ -85,11 +85,13 @@ protected:
 	
 	char m_path[FILE_MAX];
 	char m_exr_codec;
+	bool m_exr_half_float;
 	LayerList m_layers;
 	const char *m_viewName;
 	
 public:
-	OutputOpenExrMultiLayerOperation(const RenderData *rd, const bNodeTree *tree, const char *path, char exr_codec, const char *viewName);
+	OutputOpenExrMultiLayerOperation(const RenderData *rd, const bNodeTree *tree, const char *path,
+	                                 char exr_codec, bool exr_half_float, const char *viewName);
 	
 	void add_layer(const char *name, DataType datatype, bool use_layer);
 	
@@ -102,7 +104,8 @@ public:
 	bool isFileOutputOperation() const { return true; }
 };
 
-void add_exr_channels(void *exrhandle, const char *layerName, const DataType datatype, const char *viewName, const size_t width, float *buf);
+void add_exr_channels(void *exrhandle, const char *layerName, const DataType datatype, const char *viewName,
+                      const size_t width, bool use_half_float, float *buf);
 void free_exr_channels(void *exrhandle, const RenderData *rd, const char *layerName, const DataType datatype);
 int get_datatype_size(DataType datatype);
 
diff --git a/source/blender/imbuf/intern/openexr/openexr_api.cpp b/source/blender/imbuf/intern/openexr/openexr_api.cpp
index e805d3dc25c..72288149846 100644
--- a/source/blender/imbuf/intern/openexr/openexr_api.cpp
+++ b/source/blender/imbuf/intern/openexr/openexr_api.cpp
@@ -654,6 +654,8 @@ typedef struct ExrHandle {
 
 	ListBase channels;  /* flattened out, ExrChannel */
 	ListBase layers;    /* hierarchical, pointing in end to ExrChannel */
+
+	int num_half_channels;  /* used during filr save, allows faster temporary buffers allocation */
 } ExrHandle;
 
 /* flattened out channel */
@@ -666,6 +668,7 @@ typedef struct ExrChannel {
 	float *rect;                     /* first pointer to write in */
 	char chan_id;                    /* quick lookup of channel char */
 	int view_id;                     /* quick lookup of channel view */
+	bool use_half_float;             /* when saving use half float for file storage */
 } ExrChannel;
 
 
@@ -783,7 +786,10 @@ static const char *imb_exr_insert_view_name(const char *passname, const char *vi
 /* adds flattened ExrChannels */
 /* xstride, ystride and rect can be done in set_channel too, for tile writing */
 /* passname does not include view */
-void IMB_exr_add_channel(void *handle, const char *layname, const char *passname, const char *viewname, int xstride, int ystride, float *rect)
+void IMB_exr_add_channel(void *handle,
+                         const char *layname, const char *passname, const char *viewname,
+                         int xstride, int ystride, float *rect,
+                         bool use_half_float)
 {
 	ExrHandle *data = (ExrHandle *)handle;
 	ExrChannel *echan;
@@ -823,6 +829,11 @@ void IMB_exr_add_channel(void *handle, const char *layname, const char *passname
 	echan->xstride = xstride;
 	echan->ystride = ystride;
 	echan->rect = rect;
+	echan->use_half_float = use_half_float;
+
+	if (echan->use_half_float) {
+		data->num_half_channels++;
+	}
 
 	exr_printf("added channel %s\n", echan->name);
 	BLI_addtail(&data->channels, echan);
@@ -840,8 +851,10 @@ int IMB_exr_begin_write(void *handle, const char *filename, int width, int heigh
 
 	bool is_singlelayer, is_multilayer, is_multiview;
 
-	for (echan = (ExrChannel *)data->channels.first; echan; echan = echan->next)
-		header.channels().insert(echan->name, Channel(Imf::FLOAT));
+	for (echan = (ExrChannel *)data->channels.first; echan; echan = echan->next) {
+		header.channels().insert(echan->name,
+		                         Channel(echan->use_half_float ? Imf::HALF : Imf::FLOAT));
+	}
 
 	openexr_header_compression(&header, compress);
 	BKE_stamp_info_callback(&header, stamp, openexr_header_metadata_callback);
@@ -911,6 +924,8 @@ void IMB_exrtile_begin_write(void *handle, const char *filename, int mipmap, int
 
 	/* assign channels  */
 	for (echan = (ExrChannel *)data->channels.first; echan; echan = echan->next) {
+		/* Tiles are expected to be saved with full float currently. */
+		BLI_assert(echan->use_half_float == 0);
 
 		echan->m->internal_name = echan->m->name;
 		echan->m->part_number = echan->view_id;
@@ -965,7 +980,7 @@ int IMB_exr_begin_read(void *handle, const char *filename, int *width, int *heig
 			GetChannelsInMultiPartFile(*data->ifile, channels);
 
 			for (size_t i = 0; i < channels.size(); i++) {
-				IMB_exr_add_channel(data, NULL, channels[i].name.c_str(), channels[i].view.c_str(), 0, 0, NULL);
+				IMB_exr_add_channel(data, NULL, channels[i].name.c_str(), channels[i].view.c_str(), 0, 0, NULL, false);
 		
 				echan = (ExrChannel *)data->channels.last;
 				echan->m->name = channels[i].name;
@@ -1062,12 +1077,33 @@ void IMB_exr_write_channels(void *handle)
 	ExrChannel *echan;
 
 	if (data->channels.first) {
-		for (echan = (ExrChannel *)data->channels.first; echan; echan = echan->next) {
-			/* last scanline, stride negative */
-			float *rect = echan->rect + echan->xstride * (data->height - 1) * data->width;
+		const size_t num_pixels = ((size_t)data->width) * data->height;
+		half *rect_half = NULL, *current_rect_half;
+
+		/* We allocate teporary storage for half pixels for all the channels at once. */
+		if (data->num_half_channels != 0) {
+			rect_half = (half*)MEM_mallocN(sizeof(half) * data->num_half_channels * num_pixels, __func__);
+			current_rect_half = rect_half;
+		}
 
-			frameBuffer.insert(echan->name, Slice(Imf::FLOAT,  (char *)rect,
-			                                      echan->xstride * sizeof(float), -echan->ystride * sizeof(float)));
+		for (echan = (ExrChannel *)data->channels.first; echan; echan = echan->next) {
+			/* Writting starts from last scanline, stride negative. */
+			if (echan->use_half_float) {
+				float *rect = echan->rect;
+				half *cur = current_rect_half;
+				for (size_t i = 0; i < num_pixels; ++i, ++cur) {
+					*cur = rect[i * echan->xstride];
+				}
+				half *rect_to_write = current_rect_half + (data->height - 1) * data->width;
+				frameBuffer.insert(echan->name, Slice(Imf::HALF,  (char *)rect_to_write,
+				                                      sizeof(half), -data->width * sizeof(half)));
+				current_rect_half += num_pixels;
+			}
+			else {
+				float *rect = echan->rect + echan->xstride * (data->height - 1) * data->width;
+				frameBuffer.insert(echan->name, Slice(Imf::FLOAT,  (char *)rect,
+				                                      echan->xstride * sizeof(float), -echan->ystride * sizeof(float)));
+			}
 		}
 
 		data->ofile->setFrameBuffer(frameBuffer);
@@ -1077,6 +1113,10 @@ void IMB_exr_write_channels(void *handle)
 		catch (const std::exception& exc) {
 			std::cerr << "OpenEXR-writePixels: ERROR: " << exc.what() << std::endl;
 		}
+		/* Free temporary buffers. */
+		if (rect_half != NULL) {
+			MEM_freeN(rect_half);
+		}
 	}
 	else {
 		printf("Error: attempt to save MultiLayer without layers.\n");
@@ -1518,7 +1558,7 @@ static ExrHandle *imb_exr_begin_read_mem(IStream &file_stream, MultiPartInputFil
 	imb_exr_get_views(*data->ifile, *data->multiView);
 
 	for (size_t i = 0; i < channels.size(); i++) {
-		IMB_exr_add_channel(data, NULL, channels[i].name.c_str(), channels[i].view.c_str(), 0, 0, NULL);
+		IMB_exr_add_channel(data, NULL, channels[i].name.c_str(), channels[i].view.c_str(), 0, 0, NULL, false);
 
 		echan = (ExrChannel *)data->channels.last;
 		echan->m->name = channels[i].name;
diff --git a/source/blender/imbuf/intern/openexr/openexr_multi.h b/source/blender/imbuf/intern/openexr/openexr_multi.h
index 77fa420322e..97e8042caa6 100644
--- a/source/blender/imbuf/intern/openexr/openexr_multi.h
+++ b/source/blender/imbuf/intern/openexr/openexr_multi.h
@@ -52,7 +52,11 @@ struct StampData;
 
 void *IMB_exr_get_handle(void);
 void *IMB_exr_get_handle_name(const char *name);
-void    IMB_exr_add_channel(void *handle, const char *layname, const char *passname, const char *view, int xstride, int ystride, float *rect);
+void  IMB_exr_add_channel(void *handle,
+                          const char *layname, const char *passname, const char *view,
+                          int xstride, int ystride,
+                          float *rect,
+                          bool use_half_float);
 
 int     IMB_exr_begin_read(void *handle, const char *filename, int *width, int *height);
 int     IMB_exr_begin_write(void *handle, const char *filename, int width, int height, int compress, const struct StampData *stamp);
diff --git a/source/blender/imbuf/intern/openexr/openexr_stub.cpp b/source/blender/imbuf/intern/openexr/openexr_stub.cpp
index 1a2ae7a97e1..3ad23456b9f 100644
--- a/source/blender/imbuf/intern/openexr/openexr_stub.cpp
+++ b/source/blender/imbuf/intern/openexr/openexr_stub.cpp
@@ -35,7 +35,8 @@
 void   *IMB_exr_get_handle          (void) {return NULL;}
 void   *IMB_exr_get_handle_name     (const char * /*name*/) { return NULL;}
 void    IMB_exr_add_channel         (void * /*handle*/, const char * /*layname*/, const char * /*passname*/, const char * /*view*/,
-                                     int /*xstride*/, int /*ystride*/, float * /*rect*/) { }
+                                     int /*xstride*/, int /*ystride*/, float * /*rect*/,
+                                     bool /*use_half_float*/) { }
 
 int     IMB_exr_begin_read          (void * /*handle*/, const char * /*filename*/, int * /*width*/, int * /*height*/) { return 0;}
 int     IMB_exr_begin_write         (void * /*handle*/, const char * /*filename*/, int /*width*/, int /*height*/, int /*compress*/, const struct StampData * /*stamp*/) { return 0;}
diff --git a/source/blender/render/intern/source/render_result.c b/source/blender/render/intern/source/render_result.c
index ddd9859ce54..2af6a383145 100644
--- a/source/blender/render/intern/source/render_result.c
+++ b/source/blender/render/intern/source/render_result.c
@@ -502,7 +502,7 @@ static RenderPass *render_layer_add_pass(RenderResult *rr, RenderLayer *rl, int
 	if (rl->exrhandle) {
 		int a;
 		for (a = 0; a < channels; a++)
-			IMB_exr_add_channel(rl->exrhandle, rl->name, name_from_passtype(passtype, a), viewname, 0, 0, NULL);
+			IMB_exr_add_channel(rl->exrhandle, rl->name, name_from_passtype(passtype, a), viewname, 0, 0, NULL, false);
 	}
 	else {
 		float *rect;
@@ -1038,6 +1038,7 @@ bool RE_WriteRenderResult(ReportList *reports, RenderResult *rr, const char *fil
 	size_t width, height;
 
 	const bool is_mono = view && !multiview;
+	const bool use_half_float = (imf->depth == R_IMF_CHAN_DEPTH_16);
 
 	width = rr->rectx;
 	height = rr->recty;
@@ -1049,12 +1050,17 @@ bool RE_WriteRenderResult(ReportList *reports, RenderResult *rr, const char *fil
 			IMB_exr_add_view(exrhandle, rview->name);
 
 			if (rview->rectf) {
-				for (a = 0; a < 4; a++)
+				for (a = 0; a < 4; a++) {
 					IMB_exr_add_channel(exrhandle, "", RGBAZ[a],
-					                    rview->name, 4, 4 * width, rview->rectf + a);
-				if (rview->rectz)
+					                    rview->name, 4, 4 * width, rview->rectf + a,
+					                    use_half_float);
+				}
+				if (rview->rectz) {
+					/* Z pass is always stored as float. */
 					IMB_exr_add_channel(exrhandle, "", RGBAZ[4],
-					                    rview->name, 1, width, rview->rectz);
+					                    rview->name, 1, width, rview->rectz,
+					                    false);
+				}
 			}
 		}
 	}
@@ -1074,9 +1080,11 @@ bool RE_WriteRenderResult(ReportList *reports, RenderResult *rr, const char *fil
 			IMB_exr_add_view(exrhandle, rview->name);
 
 			if (rview->rectf) {
-				for (a = 0; a < 4; a++)
+				for (a = 0; a < 4; a++) {
 					IMB_exr_add_channel(exrhandle, "Composite", name_from_passtype(SCE_PASS_COMBINED, a),
-					                    chan_view, 4, 4 * width, rview->rectf + a);
+					                    chan_view, 4, 4 * width, rview->rectf + a,
+					                    use_half_float);
+				}
 			}
 		}
 
@@ -1099,14 +1107,15 @@ bool RE_WriteRenderResult(ReportList *reports, RenderResult *rr, const char *fil
 				}
 
 				for (a = 0; a < xstride; a++) {
-
 					if (rpass->passtype) {
 						IMB_exr_add_channel(exrhandle, rl->name, name_from_passtype(rpass->passtype, a), chan_view,
-						                    xstride, xstride * width, rpass->rect + a);
+						                    xstride, xstride * width, rpass->rect + a,
+						                    rpass->passtype == SCE_PASS_Z ? false : use_half_float);
 					}
 					else {
 						IMB_exr_add_channel(exrhandle, rl->name, make_pass_name(rpass, a), chan_view,
-						                    xstride, xstride * width, rpass->rect + a);
+						                    xstride, xstride * width, rpass->rect + a,
+						                    use_half_float);
 					}
 				}
 			}