//
// This confidential and proprietary software may be used only as
// authorised by a licensing agreement from ARM Limited
// (C) COPYRIGHT 2020 ARM Limited
// ALL RIGHTS RESERVED
// The entire notice above must be reproduced on all authorised
// copies and copies may only be made to the extent permitted
// by a licensing agreement from ARM Limited.

=== Image Operators

==== RESIZE

Resizes a tensor. Resize is only allowed in the H and W dimensions. In expected use, stride_y is approximately (IH<<shift)/OH and stride_x is approximately (IW<<shift)/OW. OH and OW are also supplied as inputs since there may be off by one errors if calculating OH and OW from the strides.

*Arguments:*

|===
|Argument|Type|Name|Shape|Description

|Input|in_t*|input|[N,IH,IW,C]|Input tensor
|Attribute|int*|output_size|[2]|[OH,OW]
|Attribute|int16*|stride|[2]|[stride_y, stride_x]
|Attribute|int16*|offset|[2]|[offset_y, offset_x]
|Attribute|int|shift|Shift value
|Attribute|mode_t|mode|-|BILINEAR or NEAREST
|Output|out_t*|output|[N,OH,OW,C]|Output tensor
|===

*Quantization Parameters:*

None

*Operation Function*

[source,c]
----
assert(0<shift && shift<=11); // prevent int32_t accumulator overflow for in_t==int8_t
assert(-stride_y < offset_y && offset_y < (IH<<shift)-(OH-1)*stride_y)
assert(-stride_x < offset_x && offset_x < (IH<<shift)-(OW-1)*stride_x)
for_each (0<=n<N, 0<=oy<OH, 0<=ox<OW; 0<=c<C) {
    y = oy * stride_y + offset_y
    x = ox * stride_x + offset_x
    iy = y >> shift; dy = y - (iy<<shift);
    ix = x >> shift; dx = x - (ix<<shift);
    iy0 = apply_max(iy,0);
    iy1 = apply_mix(iy,IW-1);
    ix0 = apply_max(ix,0);
    ix1 = apply_min(ix,IH-1);
    if (mode==BILINEAR) {
        v00 = tensor_read<in_t>(input, [N,IH,IW,C], [n,iy0,ix0,c])
        v01 = tensor_read<in_t>(input, [N,IH,IW,C], [n,iy0,ix1,c])
        v10 = tensor_read<in_t>(input, [N,IH,IW,C], [n,iy1,ix0,c])
        v11 = tensor_read<in_t>(input, [N,IH,IW,C], [n,iy1,ix1,c])
        acc_t acc = v00*((1<<shift)-dy)*((1<<shift)-dx)
        acc = acc + v01*((1<<shift)-dy)*dx
        acc = acc + v10*dy*((1<<shift)-dx)
        acc = acc + v11*dy*dx
        tensor_write<acc_t>(output, [N,OH,OW,C], [n,oy,ox,c], acc)
    } else if (mode==NEAREST) {
        iy = (dy>>(shift-1))!=0 ? iy1 : iy0;
        ix = (dx>>(shift-1))!=0 ? ix1 : ix0;
        v = tensor_read<in_t>(input, [N,IH,IW,C], [n,iy,ix,c]);
        tensor_write<acc_t>(output, [N,OH,OW,C], [n,oy,ox,c], v)
    }
}
----

*Supported Data Types:*

|===
|Profile|Mode|in_t|out_t

|Any|signed 8,  bilinear|int8|int32
|Any|signed 8,  nearest |int8|int8
|Any|signed 16, bilinear|int16|int48
|Any|signed 16, nearest |int16|int16
|===

*Scaling Modes:*
|===
|Mode|Description

|NEAREST|Nearest Neighbor
|BILINEAR|Bilinear interpoloation
|===